To provide foamable pellets which. when added to a base resin, enable the base resin to be injection molded into a foam with a high expansion ratio irrespective of the type of the base resin by kneading and molding a mixture of an ethylene/α-olefin copolymer and a foaming agent.

A resin component comprising 80-100 wt.% ethylene/α-olefin copolymer which is synthesized from ethylene and a 5C or higher α-olefin in the presence of a metallocene catalyst and has a density of 0.89 g/cm3, a melt index of 0.5-10 g/10 min, and a maximum melting peak temperature by DSC of 60-100°C and an olefinic thermoplastic elastomer optionally compounded is mixed and kneaded with 1-30 wt.% foaming agent and them molded to give foamable pellets. Preferably, the foaming agent is selected from among azo compounds, hydrazine derivatives, and carbonates. A foaming accelerator and/or a foaming retarder may be added, if necessary. A base resin is compounded with the foamable pellets in an amount of 1-30 wt.% of the base resin and foamed by injection molding on a surfacing material in a metal mold to give the objective molded foam.