| Date
|
Constituency
|
Incumbent
|
Party
|
New member
|
Party
|
Notes
|
| 11 December 2008
|
Proportional representation
|
Lee Han-jung
|
|
Creative Korea
|
Yu Won-il
|
|
Creative Korea
|
Incumbent's election invalidated on 11 December 2008; replaced by the next member in the Creative Korea list.
|
| 3 March 2009
|
Proportional representation
|
Lee Dal-gon
|
|
Grand National
|
Lee Doo-ah
|
|
Grand National
|
Incumbent resigned on 3 March 2009 upon appointment as Minister of Public Administration and Security; replaced by the next member in the Grand National list.
|
| 29 April 2009
|
Bupyeong B, Incheon
|
Koo Bon-chul
|
|
Grand National
|
Hong Young-pyo
|
|
Democratic
|
Incumbent's election invalidated on 15 January 2009. New member by-elected.
|
| Buk, Ulsan
|
Yoon Doo-hwan
|
|
Grand National
|
Cho Seung-soo
|
|
New Progressive
|
Incumbent lost seat on 12 March 2009. New member by-elected.
|
| Wansan A, Jeonju, North Jeolla Province
|
Lee Moo-young
|
|
Independent
|
Shin Kuhn
|
|
Independent
|
Incumbent's election invalidated on 11 December 2008. New member by-elected.
|
| Deokjin, Jeonju, North Jeolla Province
|
Kim Se-ung
|
|
Democratic
|
Chung Dong-young
|
|
Independent
|
Incumbent's election invalidated on 24 December 2008. New member by-elected.
|
| Gyeongju, North Gyeongsang Province
|
Kim Il-yun
|
|
Independent (elected as Pro-Park)
|
Jung Soo-sung
|
|
Independent
|
Incumbent's election invalidated on 24 December 2008. New member by-elected.
|
| 28 October 2009
|
Jangan, Suwon, Gyeonggi Province
|
Park Jong-hee
|
|
Grand National
|
Lee Chan-yeol
|
|
Democratic
|
Incumbent lost seat on 10 September 2009. New member by-elected.
|
| Sangnok B, Ansan, Gyeonggi Province
|
Hong Jang-pyo
|
|
Grand National (elected as Pro-Park)
|
Kim Young-hwan
|
|
Democratic
|
Incumbent's election invalidated on 23 July 2009. New member by-elected.
|
| Gangneung, Gangwon Province
|
Choi Wook-cheul
|
|
Independent
|
Kweon Seong-dong
|
|
Grand National
|
Incumbent's election invalidated on 23 July 2009. New member by-elected.
|
| Jeungpyeong–Jincheon–Gwisan–Eumseong, North Chungcheong Province
|
Kim Jong-yull
|
|
Democratic
|
Jong Bum-goo
|
|
Democratic
|
Incumbent lost seat on 24 September 2009. New member by-elected.
|
| Yangsan, South Gyeongsang Province
|
Heo Beom-do
|
|
Grand National
|
Park Hee-tae
|
|
Grand National
|
Incumbent's election invalidated on 23 June 2009. New member by-elected.
|
| 3 November 2009
|
Proportional representation
|
Jeong Kuk-kyo
|
|
Democratic
|
Kim Jinai
|
|
Democratic
|
Incumbent's election invalidated on 9 July 2009; replaced by the next member in the Democratic list.
|
| Proportional representation
|
Yang Jeong-lyea
|
|
Pro-Park
|
Kim Hye-seong
|
|
Pro-Park
|
Incumbent's election invalidated on 14 May 2009; replaced by the next member in the Pro-Park list.
|
| Proportional representation
|
Suh Chung-won
|
|
Pro-Park
|
Yoon Sang-il
|
|
Pro-Park
|
Incumbent's election invalidated on 14 May 2009; replaced by the next member in the Pro-Park list.
|
| Proportional representation
|
Kim Noh-sik
|
|
Pro-Park
|
Kim Chung
|
|
Pro-Park
|
Incumbent's election invalidated on 14 May 2009; replaced by the next member in the Pro-Park list.
|
| 16 July 2010
|
Proportional representation
|
Chung Jin-suk
|
|
Grand National
|
Kim Sung-dong
|
|
Grand National
|
Incumbent resigned on 16 July 2010 upon appointment as Senior Presidential Secretary for Political Affairs; replaced by the next member in the Grand National list.
|
| 28 July 2010
|
Eunpyeong B, Seoul
|
Moon Kook-hyun
|
|
Creative Korea
|
Lee Jae-oh
|
|
Grand National
|
Incumbent's election invalidated on 22 October 2009. New member by-elected.
|
| Gyeyang B, Incheon
|
Song Young-gil
|
|
Democratic
|
Lee Sang-kwon
|
|
Grand National
|
Incumbent resigned on 26 April 2010 to run in the 2010 Incheon mayoral election. New member by-elected.
|
| Nam, Gwangju
|
Kang Woon-tae
|
|
Independent
|
Chang Byoung-wan
|
|
Democratic
|
Incumbent resigned on 7 May 2010 to run in the 2010 Gwangju mayoral election. New member by-elected.
|
| Wonju, Gangwon Province
|
Lee Ke-jin
|
|
Grand National
|
Park Woo-soon
|
|
Democratic
|
Incumbent resigned on 30 April 2010 to run in the 2010 Gangwon Province gubernatorial election. New member by-elected.
|
| Taebaek–Yeongwol–Pyeongchang–Jeongseon, Gangwon Province
|
Lee Kwang-jae
|
|
Democratic
|
Choi Jong-won
|
|
Grand National
|
Incumbent resigned on 28 April 2010 to run in the 2010 Gangwon Province gubernatorial election. New member by-elected.
|
| Cheolwon–Hwacheon–Yanggu–Inje, Gangwon Province
|
Lee Yong-sam
|
|
Democratic
|
Han Ki-ho
|
|
Grand National
|
Incumbent died on 20 January 2010. New member by-elected.
|
| Cheonan B, South Chungcheong Province
|
Park Sang-don
|
|
Liberty Forward
|
Kim Ho-yeon
|
|
Grand National
|
Incumbent resigned on 4 May 2010 to run in the 2010 South Chungcheong Province gubernatorial election. New member by-elected.
|
| Chungju, North Chungcheong Province
|
Lee Si-jong
|
|
Democratic
|
Yoon Jin-sik
|
|
Grand National
|
Incumbent resigned on 12 April 2010 to run in the 2010 North Chungcheong Province gubernatorial election. New member by-elected.
|
| 9 September 2010
|
Proportional representation
|
Lim Doo-sung
|
|
Grand National
|
Choi Kyung-hee
|
|
Grand National
|
Incumbent's election invalidated on 9 September 2010; replaced by the next member in the Grand National list.
|
| 5 April 2011
|
Proportional representation
|
Choi Moon-soon
|
|
Democratic
|
Kim Hak-jae
|
|
Democratic
|
Incumbent resigned on 5 April 2011 to run in the 2011 Gangwon Province gubernatorial by-election; replaced by the next member in the Democratic list.
|
| 27 April 2011
|
Bundang B, Seongnam, Gyeonggi Province
|
Yim Tae-hee
|
|
Grand National
|
Sohn Hak-kyu
|
|
Democratic
|
Incumbent resigned on 1 October 2010 upon appointment as Chief of Staff to the President. New member by-elected.
|
| Suncheon, South Jeolla Province
|
Suh Gab-won
|
|
Democratic
|
Kim Sun-dong
|
|
Democratic Labor
|
Incumbent lost seat on 27 January 2011. No by-election held.
|
| Gimhae B, South Gyeongsang Province
|
Choi Chul-kook
|
|
Democratic
|
Kim Tae-ho
|
|
Grand National
|
Incumbent lost seat on 10 December 2010. No by-election held.
|
| 9 June 2011
|
Gangnam B, Seoul
|
Gong Sung-jin
|
|
Grand National
|
Seat remained vacant
|
Incumbent's election invalidated on 9 June 2011. No by-election held.
|
| 11 June 2011
|
Nowon A, Seoul
|
Hyun Gyoung-byoung
|
|
Grand National
|
Seat remained vacant
|
Incumbent's election invalidated on 11 June 2011. No by-election held.
|
| 4 August 2011
|
Seongbuk B, Seoul
|
Kim Hyo-jae
|
|
Grand National
|
Seat remained vacant
|
Incumbent resigned on 4 August 2011 upon appointment as Senior Presidential Secretary for Political Affairs. No by-election held.
|
| 28 September 2011
|
Jung, Seoul
|
Na Kyung-won
|
|
Grand National
|
Seat remained vacant
|
Incumbent resigned on 28 September 2011 to run in the 2011 Seoul mayoral by-election. No by-election held.
|
| 4 October 2011
|
Proportional representation
|
Kim Kum-lae
|
|
Grand National
|
Lee Young-yea
|
|
Grand National
|
Incumbent resigned on 4 October 2011 upon appointment as Minister of Gender Equality and Family; replaced by the next member in the Grand National list.
|
| 25 January 2012
|
Proportional representation
|
Yu Won-il
|
|
Creative Korea
|
Sun Kyung-sik
|
|
Creative Korea
|
Incumbent resigned on 25 January 2012; replaced by the next member in the Creative Korea list.
|
| 13 March 2012
|
Proportional representation
|
Kim Choong-joh
|
|
Democratic United
|
Seat remained vacant
|
Incumbent lost seat on 13 March 2012.
|
| 15 March 2012
|
Dongdaemun A, Seoul
|
Jang Kwang-keun
|
|
Saenuri
|
Seat remained vacant
|
Incumbent's election invalidated on 15 March 2012. No by-election held.
|
| 11 May 2012
|
Uijeongbu B, Gyeonggi Province
|
Kang Sung-jong
|
|
Democratic United
|
Seat remained vacant
|
Incumbent lost seat on 11 May 2012. No by-election held.
|
Members of the National Assembly of South Korea