The purpose of this study was to determine the effects of executive function on emotional regulation and emotional clarity, and to explore whether emotional clarity mediates the relationship between executive function and emotional regulation in early adulthood. For this purpose, an operation span task(OSPAN)(Kane et at., 2001) was applied to 101 participants in Seoul and Gyeonggi-do to measure execution function, and the Emotion Regulation Questionnaire(ERQ) and Trait Meta-Mood Scale(TMMS) were used to measure emotional regulation(reappraisal and suppression) and emotional clarity. Study results showed executive function had a significant relationship with both sub-variants of emotional regulation, ‘reappraisal and suppression’, and emotional clarity. The higher the level of executive function, the more clearly were emotions recognized, and the more ‘reappraisal’, rather than ‘suppression’, was used. In addition, emotional clarity was found to mediated executive function and reappraisal. The results of this study suggest that cognitive competence, including executive function, is a major variable explaining individual differences in emotional regulation, even after adolescence and into early adulthood.