Background: Subclinical thyroid disease is characterized by abnormal thyroid stimulating hormone (TSH) levels with normal free thyroxine (T4) levels. This study aimed to verify the association between subclinical hypothyroidism and depression measured using the Patient Health Questionnaire-9 (PHQ-9) score in the Korean population. Methods: This cross-sectional study included 1,786 adults aged ≥19 years with normal free T4 levels and serum TSH levels ≥0.45 mIU/L who had participated in the Korea National Health and Nutrition Examination Survey (KNHANES) 2014. The PHQ-9 was first introduced in the KNHANES to detect depression (PHQ score of ≥10). Serum TSH level of 0.45–4.49 mIU/L was defined as the reference range. The association between subclinical hypothyroidism and depression according to gender and age was evaluated using the binary logistic regression analysis after adjusting for age, education, and body mass index. Results: There was no association between subclinical hypothyroidism and depression according to gender. The odds ratio for depression was 2.498 (95% confidence interval [CI], 0.905–6.895; P=0.077) in men and 0.727 (95% CI, 0.352–1.503; P=0.390) in women. Additionally, there was no association between subclinical hypothyroidism and depression according to age. Conclusion These results suggest that subclinical hypothyroidism was not associated with depression in Korean adults.