The present invention provides a process for producing a foamed resin article, the process comprising: a step (the first step) of impregnating any one crystalline thermoplastic resin or resin composition containing, as an elementary ingredient, a crystalline thermoplastic resin selected from a certain group, under an elevated pressure which is not lower than the critical pressure of a substance with which the selected crystalline thermoplastic resin or resin composition is to be impregnated, with a fluid of the substance, and a step (the second step) of releasing the resin or resin composition impregnated with the substance from the foregoing pressurized condition in a period of less than 10 seconds.