To increase hardness and to improve side supportability by biting skin into many closed small recesses disposed in a side support section and adhering the skin, thereby forming recessed parts for decoration.

A pad 2 is constituted by simultaneously expansion molding the many small recesses 10 and hollow grooves 11 and 12 in the built-up side support section 15 as well as hollow grooves 13 for forming hollow grooves for ornamentation on a front part side at the time of molding. The many small recesses 10 are, therefore, integrally foamed in the side support section 15 of a pad 1. The adhesive is sufficiently adhered into the respective small recesses 10, the hollow grooves 11 and 12 and the hollow grooves 13 to form the cured layers of the adhesive in such a manner that the skin 2 is bitten and adhered into the respective small recesses 10, the hollow grooves 11 and 12 and the hollow grooves 13. Since the seat is constituted by forming such recessed parts for ornamentation, the side support of the seat is made rigid and the side supportability is improved. In addition, there is no odd feel at the time of use and a comfortable feel to seat is obtained. Since the pad may be formed with one kind of foams, the moldability is improved as well.