PROBLEM TO BE SOLVED: To obtain a new compound having an excellent glucosidase inhibitory activity, useful as a therapeutic agent for diabetes by making the compound include a polyhydroxyazepane (7-membered amine). SOLUTION: This compound is shown by the formula [R1 to R4 are each H, a (substituted) alkyl or the like] such as (3S,4R, 5R,6R)-hexahydro-4- methyloxy-3,5,6-trihydroxy-1H-azepine. The compound of the formula is obtained by reacting pyranose with p-toluenesulfonyl chloride of 1-3 times as much as the molar amount of the compound in a solvent (e.g. pyridine, etc.), at -10 to 15 deg.C for about 4-48 hours to give a 6-O-arylsulfonyl pyranose and reacting the 6-O-arylsulfonylpyranose with sodium azide of 2-50 times as much as the substance in a polar solvent (e.g. water, etc.), at 50-100 deg.C for about 2-12 hours to give 6-azido-6-deoxypyranose and reducing 6-azido-6-deoxypyranose with ammonium formate in the presence of palladium-carbon at 10-100 deg.C for 3-50 hours.