This study examined how the consumers’ perception of GM food affects their purchasing behavior. In addition, this study investigated how the amount of knowledge a consumer has regarding GM food affects their perception of this type of food. The quantitative research method was used to collect data. The data from a self-administered survey, which was conducted in South Korea, was analyzed using descriptive analysis, ANOVA, factor analysis, and multiple regression analysis methods. The results of the survey indicate that most respondents may have unknowingly purchased GM food. Further, the respondents reported that they likely had known about or had heard of GM food. In addition, the survey indicated that the amount of knowledge possessed by the respondents regarding GM food greatly affected their perceptions of this type of food. These findings will contribute to the current GM food market by providing the food market with additional information relating to the consumers’ perceptions of GM food.