Master batch for expansion molding and foam molded body

A masterbatch for foam molding, comprising:

• a base resin;
• and
• a thermally expandable microcapsule,
• the masterbatch having a true specific gravity of 0.90 g/cm3 or more,
• the base resin containing an olefin elastomer having a melt index of 2 to 20 g/10 min at 190° C. pressurized at 2.16 kg,
• the thermally expandable microcapsule having a bulk specific gravity of 0.40 g/cm3 or more,
• the masterbatch containing the thermally expandable microcapsule in an amount of 40 to 300 parts by weight relative to 100 parts by weight of the base resin,
• a difference between a foaming starting temperature of the thermally expandable microcapsule and a melting point of the olefin elastomer being 50° C. or more,
• the olefin elastomer comprising a propylene elastomer containing an ethylene component and propylene component, and having a melting point of 50° C. to 120° C., and
• the propylene elastomer having a content of the ethylene component of 3 to 13% by weight.