Method for producing an alkylene oxide adduct and its derivatives

A use of a normal manufacturing equipment, while suppressing the production of by-products, it is possible to obtain high molecular weight alkylene oxide adduct, a method for manufacturing an alkylene oxide adduct, and provides a method for producing a derivative thereof to. A method for manufacturing a alkylene oxide adduct according to the present invention, the hydroxyl group-containing saturated compound by addition reaction of alkylene oxide to a method for obtaining an alkylene oxide adduct, average per 1 mol of hydroxyl group-containing saturated compound wherein the initial step of obtaining an alkylene oxide low mol adduct by adding 20 moles of alkylene oxide, and an additional molar number adjusting step further adding an alkylene oxide to alkylene oxide low-mol adduct prepared in the initial step the in molar number of addition adjusting step, characterized by using a portion of the amount in the resulting alkylene oxide low mol adduct total amount in the initial step.