本文主要目的在於探討為何在2004年台灣總統大選與公民投票合併舉行時，兩項選舉的投票率有明顯的落差，是哪些因素影響總統大選的高投票率以及公民投票的低投票率？本文分析TEDS 2004年總統大選面訪資料發現，影響選民參與總統大選以及公民投票的因素是相當不同的，在總統大選方面，對於不同候選人的利益落差以及教育程度是具有影響力的變數，而政治效能感以及動員則沒有影響力，本文以為這是因為在台灣的投票成本相對較低的緣故。在公民投票方面，對於不同候選人的利益落差、政治效能感以及動員皆對於民眾的參與具有影響。另一方面，本文試圖探索不希望公民投票通過的選民，是否會依據對於現實世界可能發生狀況的不同判斷，而做出棄權或是投反對票的不同選擇。結果發現，這兩種投票決定對於不希望公民投票通過的選民來說，是差異不大的。

The goal of this paper is exploring why - despite the referenda and presidential election being jointly conducted - there is a huge gap between the turnout rates for the presidential election and referenda vote in Taiwan in 2004. After analyzing the 2004 TEDS presidential election survey data, the authors find that the determinants of whether to vote or not in the presidential election and referenda are different. For the presidential election, differential benefit and level of education are influential factors while political efficacy and mobilization are not. The authors suspect that the high turnout rate of the presidential election in Taiwan results from the relatively low cost of voting. For the referenda: differential benefit, political efficacy and mobilization are all influencing factors. On the other hand, the authors attempt to explore whether the difference between abstention and voting no forthose who do not want the referenda to pass - depends on their perception of the state of the world. The result is that this variable fails to explain the choice of voting no. The research findings infer that for those who do not want the referenda to pass, the choice of abstention and voting "no" does not make a difference.