PURPOSE: To obtain the subject compound having long-chain alkyl groups and useful as a surfactant with high purity and high yield on one stage by bringing a saccharide to react with a long-chain alcohol in a nonpolar solvent in the presence of an emulsifier.

CONSTITUTION: By bringing saccharide to react with an 8-24C alcohol (such as decanol, stearyl alcohol or the like) in a non-polar solvent (suitably, hexane, benzene or the like), preferably, at 80 to 120°C in the presence of an emulsifier (suitably, paraffine sulfonate, an 8-24C alkyl polyglycoside or the like), an alkyl polyglycoside having an 8-24C alkyl group and an average polymerization degree of 1 to 10 is obtd. in one stage reaction. The emulsifier is used preferably in a ratio of 4 to 100% to the reaction components.