Objective: We explored the association of 3-year adherence to a dietary pattern based on nutrients that may be related to mood with the development of depressive symptoms in Japanese employees. Methods: Participants were 903 employees free from depressive symptoms at baseline and who attended the 3-year follow-up. Participants with depressive symptoms were defined as those with a score ≥16 on the Center for Epidemiologic Studies Depression Scale. Dietary patterns were derived using reduced-rank regression at baseline and at the 3-year follow-up survey using a validated, self-administered diet history questionnaire. Based on changes in dietary pattern scores between baseline and follow-up surveys, participants were categorized into four groups: Maintained high scores, improved scores, decreased scores, and maintained low scores. Logistic regression was used to estimate odds ratios of depressive symptoms according to changes in dietary pattern scores. Results: Maintaining high or improving adherence to a diet rich in vegetables, mushrooms, seaweeds, soybean products, green tea, potatoes, fruits, and fish and low in rice over 3 y was associated with a decreased risk of depressive symptoms. The multivariable-adjusted odds ratio (95% confidence intervals) of developing depressive symptoms for maintained high scores versus maintained low scores was 0.57 (0.35–0.93) and for improved scores versus maintained low scores was 0.54 (0.29–1.01). The association with the severe depressive status was more pronounced. Conclusion: Maintaining high or improving adherence to a dietary pattern derived by reduced-rank regression is associated with a lower risk of depression among Japanese employees.