This study is about how independent voters make their vote decision in presidential election focusing on electoral behaviour in South Korea. The main argument of this thesis is that voters are not very rational in voting choice when party constraints are absent. Both qualitative and quantitative approaches are employed in this study and provide a comprehensive analysis of voting behaviour of independent voters in the new democracy. In particular, the use of focus group interviews and in-depth one-to-one interviews conducted during the 2002 Korean Presidential Election provides detailed analysis of electoral behaviour in Korea. Korean voters have developed party identification, a long-term psychological attachment with a particular political party, under the institutional underdevelopment of the political parties in the new democracy. Regionalism is the predominant factor to explain partisan alignment in Korea, but ideological self-identification also accounts for the partisan alignment in new democracy. Over the last 10 years, party identification has markedly weakened in Korea, a 15 year old democracy, in contrast to experiences of other new democracies. This weakening of party identification is largely due to changes in political interest and dissatisfaction with political processes in new democracy. My findings confirm that the increase of independents and the process of partisan dealignment are closely related to a decline of electoral stability. But an increase of independent voters who are free from party constraints has not lead to an increase of rational voting behaviour in Korean presidential elections. Although independent voters are most interested in short-term considerations, such as candidate evaluation, issue stands and government performance, their voting choice is not politically rational. Independent voters are more likely to make vote decision based on insufficient information and heavily rely on candidate image rather than substance in their voting choice. Many independent voters cast their ballot based on the candidates' affective dimensions, such as integrity, empathy and appearance, rather than cognitive dimensions, such as competence to solve the nation's urgent problems.