The present invention relates to an in-mold expanded beads molded article of expanded beads of an olefin thermoplastic elastomer, a cushion for shoe sole, and a method of producing expanded beads provided with through-holes and composed of a block copolymer of a polyethylene block and an ethylene/α-olefin copolymer block, and with respect to the in-mold expanded beads molded article of expanded beads of an olefin thermoplastic elastomer, a voidage of the expanded beads molded article is 5 to 40%; a density of the expanded beads molded article is 30 to 150 g/L; and a flexural modulus of the olefin thermoplastic elastomer that constitutes the expanded beads molded article is 10 to 100 MPa.