A compound which is useful as an active ingredient for a pharmaceutical composition for treating urine storage dysfunction, voiding dysfunction, lower urinary tract dysfunction, and the like. The present inventors have found that a 2-aminothiazole derivative has an excellent muscarinic M3 receptor-positive allosteric modulator activity and is expected as an agent for preventing or treating bladder/urinary tract diseases associated with bladder contractions via a muscarinic M3 receptor, thereby completing the present invention. 2-aminothiazole derivative or a salt thereof of the present invention is expected as an agent for preventing or treating bladder/urinary tract diseases associated with bladder contractions via a muscarinic M3 receptor, for example voiding dysfunction such as underactive bladder.