[Problem] To provide a compound useful as an MC4 receptor agonist.[Means for Solution] The present inventors studied MC4 receptor agonists, and have found that a piperazine derivative has an MC4 receptor agonistic action, thereby completing the present invention. The piperazine derivative of the present invention has an MC4 receptor agonistic action, and can be used as an agent for preventing or treating bladder and/or urinary tract diseases, in particular, underactive bladder, hypotonic bladder, acontractile bladder, detrusor underactivity, neurogenic bladder, urethral relaxation failure, detrusor-external urethral sphincter dyssynergia, and voiding dysfunctions in benign prostatic hyperplasia.
