Objectives: This study aimed to investigate factors influencing suicidal ideation among Korean adults. Methods: Cross-sectionaldata from the fifth Korea National Health and Nutritional Examination Survey conducted in 2012 were analyzed in this study. The subjects were categorized into three groups by subjects’ age(defined as young adults(20-39), middle-aged adults(40-59),and the elderly(60 or more). Data were analyzed by frequency, Chi-square test and multiple logistic regression using SPSS18.0. Results: The factors influencing suicidal ideation were different among three age groups. The influencing factors were(1) gender, marital status, household income, perceived stress and depression in the young adult group, (2) household income,perceived health status, perceived stress and depression in the middle-aged group, (3) gender, regular physical activity, smoking,perceived health status, perceived stress and depression in the elderly group. Conclusions: The health education consideringthe characteristics of each age group should be developed and applied to prevent adults’ suicidal ideation because the factorsinfluencing suicidal ideation were revealed differently between the age groups.