To produce the subject derivative used for a synthesis intermediate, etc., of various kinds of saccharide derivatives by dissolving or suspending saccharides in acetic acid, which is a reaction solvent, reacting the dissolved or suspended saccharides by adding acetic anhydride at a specific temperature in the presence of a catalyst and recovering the acetic acid after the reaction.

Saccharides (e.g. glucose) are dissolved or suspended in acetic acid, which is a reaction solvent, and reacted by adding acetic anhydride at 70-100°C in the presence of a catalyst (e.g. sodium acetate), and thereafter the acetic acid is recovered by distilling off the acetic acid by a distillation under reduced pressure to precipitate crystals. Further, the residue is heated and dissolved by adding toluene, etc., washed with hot water in the hot state, and cooled to recrystallize the objective acetyl derivative of the saccharide (e.g. pentaacetylglucose). The recrystallized acetyl derivative is filtrated, and the recovered acetic acid is reused. The objective acetyl derivative of the saccharides used for a synthesis intermediate of various saccharide derivatives, an emulsifying auxiliary, a resin additive and a paper strong agent, etc., is produced in an industrial scale in large quantity.