An agent for the treatment and/or prophylaxis of a mooddisorder such as a depressive disorder, major depression,dysthymia, a depression-related syndrome, a symptom ofdepression due to a physical disorder or a drug-inducedsymptom of depression is provided. The agent comprises, as anactive ingredient, a thiazole derivative represented by theformula (I) wherein R1 represents aryl or the like, and R2represents pyridyl or the like, or a pharmaceuticallyacceptable salt thereof, and the like.(see formula I)
