Japanese Parliamentary Elections 2005
The results of Japan’s recent parliamentary elections have been held up by the Japanese media as demonstrating a stunning mandate for Prime Minster Junichiro Koizumi, leader of the nation’s Liberal Democratic Party. FairVote’s analysis of the election results, however, indicates that this mandate was far from clear, with Koizumi’s party in fact winning just 38% of the popular vote.

Election System Basics: Japanese parliamentary elections employ both a winner-take-all aspect and proportional voting aspect to fill the combined 480 seats. 300 of the seats are elected from single-member districts by a simple plurality, as in the United States. An additional 180 seats are elected based on a party list proportional representation system where seats are allocated to parties based roughly on the percentage the party won in the popular vote - but without regard for any distortions that might take place in representation in the district seats. Under Japan’s system, each voter selects their single district representative, but their vote also counts toward the nationwide total or that candidate’s political party. According to the results, 67,811,069 people out of a population of 127,333,002 (roughly 50%) turned out to vote in these 2005 Mixed Member Parliamentary elections. The fact of Japan having such a hybrid system in place allows for a comparison of how single-member districts skew representation when compared to proportional voting systems. Below, we have analyzed the results of the election by calculating how skewed each party’s representation is in the single member seats and the proportionally allocated seats, when compared to their share of the national popular vote.

Over-Representation of the Liberal Democratic Party: Prime Minister Koizumi’s Liberal Democratic Party (LDP) members captured a combined 38.18% of the nationwide vote. This translated into the LDP winning an astounding 219 out of the 300 single member district seats up for grabs. This means that, under the single member district system, the LDP was able to capture 73% of the single member election seats available, despite having only won roughly 38% of the popular vote. In contrast, the LDP was awarded a more balanced number of 77 of the proportionally allocated seats representing roughly 42% of the 180 total proportional representation seats. Hence, it becomes clear that the single member system, when compared to a proportional allocation system, has the potential to greatly skew election outcomes away from fair results. In fact, the over-representation of the LDP through the single member district seats was so severe that even with the inclusion of the proportional seats, the LDP still holds 61% of the total parliamentary seats – almost 23% more seats than their share of the vote would warrant. It is through the winner-take-all single member system that Japan now has a political party with the support of less than half of voters holding more than half of the parliamentary seats.

Record Number of Women Elected: One bright spot in the election results is that women were elected in record numbers this year, owing mainly to Prime Minister Koizumi's initiative to shake up party insiders and freshen up the Liberal Democratic Party (LDP) image by boosting women's representation. Under the plan, dubbed the "female ninja" strategy, Koizumi made women's representation a priority by recruiting female candidates and placing them high up on the LDP's proportional representation party list. This meant that when the LDP was allocated its proportional representation seats, the women on the LDP list were likely to receive seats before their male counterparts lower on the list. It is through this method that the LDP tripled the number of women in its caucus from nine to twenty-six. Of the 83 freshman lawmakers elected this cycle, roughly a third were women. Though the overall number of women in the Japanese parliament still stands at a paltry 43 out of 480 seats, representing only 9% of the seats, even this modest gain would not have been possible in the winner-take-all, single member district parliamentary seats. Women running for office in the single member districts would most likely have to go head-to-head against a male candidate instead of being part of a cooperative slate of candidates, as with the proportional representation seats. This first step towards greater representation of women in parliament provides hope for future gains in Japan.

Under-Representation of the Other Parties: This problem of skewed representation in the single member district seats was witnessed over and over again for Japan’s other political parties. The Democratic Party of Japan won 52 single member seats, representing roughly 17% of the available single member seats, despite winning 31% of the nationwide popular vote - just 7% less than the Liberal Democrats. Under the proportional representation system they won 61 seats, giving them a more accurate 33% of the proportional representation seats. Overall the Democratic Party of Japan represents 23.5% of the seats

Although the New Komeito Party, a coalition partner of the Liberal Democrats, won 13% of the overall poplar vote they only won 8 seats in the single member elections, which equals 2.6% of the single member elections. However under proportional representation system they saw a fairer result, winning 23 seats, or 12.7% of the proportional seats. They represent 6% of the overall number of seats

The Japanese Communist Party (JCP) did not win any single member election seats. In spite of this they won 7% of the popular vote, and this gave them 9 seats of the proportional representation seat, which is 5% of the PR seats available. The JCP represents 2% of the overall seats.

Although the Social Democratic Party received only 5% of the popular votes, which is less the than the Japanese Communist Party, they were able to win one single member election, or  .3% of the single member elected seats. Because of this they were also awarded 6 proportional representation seats, which equals 3% of the available proportionally allocated seats. They represent 1.4% of the overall seats

There were several other groups who were not on the ballot in every prefecture and each group won less then 4% of the overall vote. Of these groups the People’s National Party won 2 single election seats and 2 PR seats for a 4 seats total. The New Party of Japan and the Shinto Daichi each won one seat each through proportional representation.

For further details, see the chart below:









% Popular Vote

Seats Received

SMD Skew

% PR Seats Received

PR Skew

% Total Seats Received

Total Skew

Liberal Democratic Party








Democratic Party
of Japan








New Clean Government Party








Japan Communist Party








Social Democratic Party








New Party Japan








People's New Party








Shinto Daichi








Other (combined)










Note: SMD means Single Member District,
PR means Proportional Representation

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