Abstract: [Problem] To provide a compound which can be used as an MC4 receptor agonist. [Means for Solution] The present inventors have investigated MC4 receptor agonists, and have found that a piperazine derivative has an action related to the agonists, thereby completing the present invention. That is, 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.