A method for producing a foam product having an outer skin is provided. The outer skin is firstly placed in a mold and then a plurality of polystyrene foam beads are introduced into the mold in order to fill a cavity of the mold with the foam beads, which are heat-bonded with one another under steam pressure subsequently. Accordingly, a surface of the outer skin, which contacts with the foam beads, is entirely heat-bonded with the foam beads. Thus, the foam product with the outer skin is produced and the foam product comprises the outer skin and a polystyrene foam core composed of the foam beads, which are heat-bonded with one another without any spaces.