| Election Name: | 2005 Tokyo prefectural election |
| Country: | Tokyo |
| Type: | parliamentary |
| Ongoing: | no |
| Previous Election: | 2001 Tokyo prefectural election |
| Previous Year: | 2001 |
| Next Election: | 2009 Tokyo prefectural election |
| Next Year: | 2009 |
| Seats For Election: | All 127 seats in the Tokyo Metropolitan Assembly |
| Majority Seats: | 64 |
| Turnout: | 43.99%(6.09%) |
| Election Date: | 3 July 2005 |
| Leader1: | Eita Yashiro |
| Party1: | Liberal Democratic Party (Japan) |
| Last Election1: | 53 |
| Seats Before1: | 53 |
| Seats1: | 48 |
| Seat Change1: | 5 |
| Popular Vote1: | 1,339,548 |
| Percentage1: | 30.7% |
| Leader2: | Banri Kaieda |
| Party2: | Democratic Party (Japan, 1998) |
| Last Election2: | 22 |
| Seats Before2: | 22 |
| Seats2: | 35 |
| Seat Change2: | 13 |
| Popular Vote2: | 1,070,893 |
| Percentage2: | 24.5% |
| Leader3: | Natsuo Yamaguchi |
| Party3: | Komeito |
| Last Election3: | 23 |
| Seats Before3: | 22 |
| Seats3: | 23 |
| Seat Change3: | 1 |
| Popular Vote3: | 786,292 |
| Percentage3: | 18.0% |
| Image4: | 共産 |
| Party4: | Japanese Communist Party |
| Leader4: | Yoshiharu Wakabayashi |
| Last Election4: | 15 |
| Seats Before4: | 15 |
| Seats4: | 13 |
| Seat Change4: | 2 |
| Popular Vote4: | 680,200 |
| Percentage4: | 15.6% |
| Image5: | ネット |
| Leader5: | Mitsuko Nishizaki |
| Party5: | Tokyo Seikatsusha Network |
| Last Election5: | 6 |
| Seats Before5: | 6 |
| Seats5: | 3 |
| Seat Change5: | 3 |
| Popular Vote5: | 181,020 |
| Percentage5: | 4.1% |
| Assembly President | |
| Before Election: | Shigeru Uchida |
| Before Party: | Liberal Democratic Party of Japan |
| After Election: | Chuuichi Kawashima |
| After Party: | Liberal Democratic Party of Japan |
Prefectural elections were held in Tokyo for the city's Metropolitan Assembly on 3 July 2005. The election was a great success for the Democratic Party of Japan which won 16 additional seats, closing in on the Liberal Democratic Party.
|-! style="background-color:#E9E9E9;text-align:left;" |Parties! style="background-color:#E9E9E9;text-align:right;" |Candidates! style="background-color:#E9E9E9;text-align:right;" |Votes! style="background-color:#E9E9E9;text-align:right;" |%! style="background-color:#E9E9E9;text-align:right;" |Seats|-| style="text-align:left;" |Liberal Democratic Party of Japan (自由民主党, Jiyū Minshutō)| style="text-align:right;" | 57| style="text-align:right;" | 1,339,548| style="text-align:right;" | 30.7| style="text-align:right;" | 48|-| style="text-align:left;" |Democratic Party of Japan (民主党, Minshutō)| style="text-align:right;" | 51| style="text-align:right;" | 1,070,893| style="text-align:right;" | 24.5| style="text-align:right;" | 35|-| style="text-align:left;" |New Komeito party (公明党, Kōmeitō)| style="text-align:right;" | 23| style="text-align:right;" | 786,292| style="text-align:right;" | 18.0| style="text-align:right;" | 23|-| style="text-align:left;" |Japanese Communist Party (日本共産党, Nihon Kyōsan-tō)| style="text-align:right;" | 43| style="text-align:right;" | 680,200| style="text-align:right;" | 15.6| style="text-align:right;" | 13|-| style="text-align:left;" |Social Democratic Party (社民党 Shamin-tō)| style="text-align:right;" | 1| style="text-align:right;" | 10,165| style="text-align:right;" | 0.2| style="text-align:right;" | 0|-| style="text-align:left;" |Tokyo Seikatsusha Network (東京・生活者ネットワーク)| style="text-align:right;" | 10| style="text-align:right;" | 181,020| style="text-align:right;" | 4.1| style="text-align:right;" | 3|-| style="text-align:left;" |Gyokaku 110-ban (行革110番)| style="text-align:right;" | 1| style="text-align:right;" | 24,259| style="text-align:right;" | 0.6| style="text-align:right;" | 1|-| style="text-align:left;" | Others| style="text-align:right;" | 4| style="text-align:right;" | 27,784| style="text-align:right;" | 0.6| style="text-align:right;" | 0|-| style="text-align:left;" | Independents| style="text-align:right;" | 30| style="text-align:right;" | 248,999| style="text-align:right;" | 5.7| style="text-align:right;" | 4|-|style="text-align:left;background-color:#E9E9E9"|Total (turnout 43.99%)|width="30" style="text-align:right;background-color:#E9E9E9"| 220|width="75" style="text-align:right;background-color:#E9E9E9"| 4,435,435|width="30" style="text-align:right;background-color:#E9E9E9"| 100.00|width="30" style="text-align:right;background-color:#E9E9E9"| 127|-| style="text-align:left;" colspan=4 |Sources:Tokyo electoral commission: 投開票結果, JANJAN: 東京都議会議員選挙, Asahi Shimbun: http://www.asahi.com/politics/2005togisen/chart/05070403.html|}NB: Results are incomplete due to lack of sources.