A resin composition for cross-linking foam molding having a polymer composition which comprises 100 parts by weight of the following component (A) and 0.5 to 20 parts by weight of the following component (B); a foaming agent; and a cross-linking agent, wherein the component (A) is an ethylene-based polymer satisfying the following conditions (a1) to (a2): (a1) the density is 860 to 935 kg/m3, and (a2) the melt flow rate (MFR) is 0.1 to 10 g/10 minutes, and the component (B) is an ethylene-α-olefin copolymer satisfying the following conditions (b1) to (b3): (b1) the density is 890 to 925 kg/m3, (b2) the intrinsic viscosity [η] determined in a tetralin solution is 4 to 15 dL/g, and (b3) the activation energy of flow (Ea) is less than 50 kJ/mol.