A foamed sheet of a base resin containing 50 to 100% by weight of a polylactic acid resin and having an apparent density of 63 to 630 kg/m3, a thickness of 0.5 to 7 mm and endothermic and exothermic calorific values of ΔHendo:2 and ΔHexo:2, respectively, as measured by heat flux differential scanning calorimetry at a heating rate of 2° C./min. The endothermic calorific value ΔHendo:2 is at least 10 J/g and the difference (ΔHendo:2−ΔHexo:2) between the endothermic calorific value ΔHendo:2 and the exothermic calorific value ΔHexo:2 is less than 40 J/g. A foam molding such as a receptacle is prepared by thermoforming the foamed sheet.