To provide a reinforcing material for expansion molding, highly effective for preventing the squeaking noise generated by the friction between a polyurethane foam and a spring member, having good affinity to the mold for expansion molding and getting excellent reinforcing effect.

The reinforcing material for expansion molding is produced by laminating a flexible nonwoven fabric having a fabric weight of 30-300 g/m2 and made of a polytrimethylene terephthalate fiber or a polybutylene terephthalate fiber having a 10% elongation stress of 0.2-1 cN/dtex to a dense nonwoven fabric having a fabric weight of 20-200 g/m2 and an apparent density of 0.08-0.40 g/cm3. It is used as a seat material of vehicles to prevent the squeaking noise generated by the friction between the polyurethane foam of the seat material and a spring member.