Disclosed is a poly(4-methyl-1-pentene) resin composition having an excellent balance between micropore formability and toughness, which can sufficiently form fine pores by drawing and does not cause a break during drawing. The poly(4-methyl-1-pentene) resin composition contains 0-90 parts by mass of a 4-methyl-1-pentene homopolymer (A) and 10-100 parts by mass of a 4-methyl-1-pentene copolymer (B) having a structural unit derived from 4-methyl-1-pentene and a structural unit derived from a C2-20 α-olefin other than 4-methyl-1-pentene. The content of the structural unit derived from a C2-20 α-olefin other than 4-methyl-1-pentene is 0.1-2.1% by mass relative to the total amount of the homopolymer (A) and the copolymer (B). The poly(4-methyl-1-pentene) resin composition also contains 0.1-800 ppm of a nucleator (C) relative to the total weight of the homopolymer (A) and the copolymer (B).