PURPOSE: To produce a polyol containing an aldehyde condensation polymer component stably dissolved or dispersed therein, by reacting aldehyde condensation polymer-forming materials in a specified polyether-polyol.

CONSTITUTION: Aldehyde condensation polymer-forming materials are reacted in a polyether-polyol at least part of which has initiator residues capable of bonding to the polymer-forming materials, whereby a polyol containing an aldehyde condensation polymer component having a high dispersion stability in which at least part of the condensation polymer is bonded to said polyether-polyol can be obtained. Said polyether-polyol is preferably one prepared by addng an epoxide to an initiator having at least two sites to which an epoxide can add, and at least one site to which at least one of the aldehyde condensation polymer forming materials can add.