Vote-buying in elections is widespread in Taiwan's electoral politics. In order to understand the causes of prevailing practice of vote-buying, this study concentrates on the candidate's incentives to buy votes. From the perspective of strategy selection, candidates try their best to maximize the votes in the electoral process, and decide their own tactics via evaluating and calculating their opponents' strategies. This research therefore regards the predictive payoff inter-actions between contenders as the point at which to illustrate the candidate's behavior of vote-buying. Accordingly, we employ the framework of Fr insufficient information game theory" in which a variety of determinants of vote-buying are considered to reach some corollaries. By analyzing these corollaries, we conclude that the vote-buying is a form of candidate's rational behavior, and that is the reason the phenomenon of vote-buying remains.