Disclosed is a thermoplastic resin foam which excels typically in strength, flexibility, cushioning properties, and strain recovery and is especially resistant to cell structure shrinkage caused by the restoring force of resin.The thermoplastic resin foam which is obtained by subjecting a thermoplastic resin composition containing a thermoplastic elastomer and an active-energy-ray-curable resin to foam molding to give a foamed structure, and irradiating the foamed structure with an active energy ray to allow the active-energy-ray-curable resin to form a cross-linked structure in the foamed structure. Also, the thermoplastic resin foam which is obtained by subjecting a thermoplastic resin composition containing a thermoplastic elastomer, an active-energy-ray-curable resin, and a thermal cross-linking agent to foam molding to give a foamed structure, irradiating the foamed structure with an active energy ray to allow the active-energy-ray-curable resin to form a cross-linked structure in the foamed structure, and heating the resulting foamed structure bearing the cross-linked structure to thereby allow the thermal cross-linking agent to form another cross-linked structure in the foamed structure.