PURPOSE: To obtain a highly elastic polyurethane foam superior in durability to polyurethane foams produced by conventional processes, by using polyoxypropylene polyoxyethylene polyols having different functionalities in a specific proportion.

CONSTITUTION: A polyurethane foam is produced from an organic polyisocyanate (e.g. an aromatic polyisocyanate) and a high-mol. polyol ingredient in the presence of a foaming agent (e.g. water), a catalyst (e.g. an amine), and a foam stabilizer (e.g. a siloxane). The polyol ingredient comprises a polyoxypropylene polyoxyethylene polyol (a) having a functionality of 3, a hydroxyl value of 20-40, and a content of terminal hydroxyethylene groups of 5-25wt.% and a polyoxypropylene polyoxyethylene polyol (b) having a functionality higher than 4, a hydroxyl value of 20-45, a content of terminal hydroxyethylene groups of 5-25wt.%, the (a)/(b) weight ratio being 30/70 to 85/15.