Disclosed is a sulfonamide compound represented by general formula (1) that can be used as an effective component in a CaSR antagonist that is extremely effective in preventing and/or treating bone diseases, such as osteoporosis. Said compound has excellent PTH secretion promoting effects. Said compound is useful as a medically effective component for preventing and/or treating osteoporosis or bone fractures, hypoparathyroidism, or other bone diseases.