Based on rational choice theory, we examine the determinants of turnout in 2008 Korean general election with aggregate-level data. Because the operational definitions of a key concept of election closeness have been confused, we provide a generalized discussion of the closeness and evaluates
similarities and difference among the definitions. We refrain from using regional dummy variables and analyze the effects of more abundant socio-economic variables on turnout. We find that closeness as well as the ratio of the elderly, population density, campaign expenditures, and number of voting stations are significantly and positively related with the turnout, but size of eligible voters, population mobility, and number of candidates are significantly and negatively related, as mostly expected. Finally, it is shown that dominance of the Grand National Party in the election is partly due to higher turnout of its supporters than the United Democratic Party(the first opposition party)’s.