Provided are compounds represented by the following formula (A-1) and formula (1), or salts thereof. The compounds of formula (A-1) and formula (1) or salts thereof have β3 adrenergic receptor agonist activity, and thus are useful as therapeutic and prophylactic agent for diabetes mellitus, obesity, hyperlipidemia, depression, diseases caused by gallstones or hypermotility of the biliary tract, diseases caused by hyperactivity of the digestive tract, interstitial cystitis, overactive bladder or urinary incontinence, or as therapeutic and prophylactic agents for diseases concomitant with decreased tears.