The present invention has its object to provide a masterbatch for foam molding, which can be suitably used for molding processes involving high shearing force, such as kneading molding, calender molding, extrusion molding, and injection molding, which shows a high expansion ratio, and which yields a foamed product with a good appearance. The present invention also has its object to provide a foamed product using the masterbatch for foam molding.A masterbatch for foam molding comprises a base resin and a thermally expandable microcapsule, the base resin being a thermoplastic resin having a melting point of 100° C. or higher, the masterbatch containing 10 to 230 parts by weight of the thermally expandable microcapsule to 100 parts by weight of the base resin, and the masterbatch having a true density of 0.80 g/cm3 or more, a bulk density of 0.35 g/cm3 or more, and a masterbatch size of 450 mg/30 pieces or more.