Despite the controversy surrounding electronic cigarette (e-cigarette) safety, global consumption has been rapidly increasing. We investigated the relationship between e-cigarette use and mental health conditions in adults of various ages.We conducted a secondary data analysis of adults aged 19 to 80 who participated in the first year of the 7th Korea National Health and Nutrition Examination Survey (2016). The total number of participants was 5469, including 3398 non-smokers, 1700 smokers who had never used e-cigarettes, and 371 smokers who had previously used e-cigarettes, selected based on self-report questionnaires. Mental health factors including stress status, depressive mood, suicide plan, and suicide attempt were assessed by self-reported questionnaire. The Patient Health Questionnaire (PHQ-9) was used to assess depressive mood, with a cut-off value of 10. The relationship between e-cigarette use and stress status with depressive mood were analyzed with adjustment for potential confounders.Both male and female smokers who previously used e-cigarettes showed higher levels of stress than non-smokers or smokers who had never used e-cigarettes. The average PHQ-9 score was higher among previous e-cigarette-using smokers relative to non-smokers and smokers who had never used e-cigarettes, regardless of gender. The number of participants with depressive mood was significantly higher in the group of smokers who previously used e-cigarettes. In multivariable-adjusted logistic regression analyses, there was a significantly higher odds ratio for higher stress in male smokers who had previously used e-cigarettes and for depressive mood in female smokers who had previously used e-cigarettes, compared with non-smokers.This study analyzed the association between adult e-cigarette use and mental health conditions, including stress and depressive mood, and showed that e-cigarette use was significantly related to both conditions in men and women.