Disclosed is a compound useful as an active ingredient for a pharmaceutical composition having an ±-amylase-inhibiting activity, particularly a pharmaceutical composition for the treatment of diabetes. Studies have been made for discovering a compound having an ±-amylase-inhibiting activity among the compounds produced by Streptomyces sp. Strain 6982 which is a ray fungus belonging to the genus streptomyces, and it is confirmed that an aminosugar compound has an ±-amylase-inhibiting activity. The aminosugar compound has an ±-amylase-inhibiting activity, and therefore can be used as a prophylactic or therapeutic agent for diabetes, obesity, NASH (non-alcoholic steatohepatitis), particularly as an ameliorating agent for postprandial blood glucose elevation.
