Disclosed is a block copolymer composition comprising a block copolymer (I) comprising at least two polymer blocks (each polymer block (S) comprising vinyl aromatic hydrocarbon monomer units) and at least one polymer block (B) comprising isoprene monomer units and 1,3-butadiene monomer units, and a polystyrene resin (II), wherein, in the block copolymer (I), the amount of the vinyl aromatic hydrocarbon monomer units, the total amount of the isoprene monomer units and the 1,3-butadiene monomer units, and the isoprene monomer unit/1,3-butadiene monomer unit weight ratio are within specific range, wherein the block copolymer (I) has a vinyl aromatic hydrocarbon block ratio (BL) within a specific range, and wherein the block copolymer (I) and the polystyrene resin (II) satisfy a relationship represented by the following formula (1):
15+0.25BL≦Wa≦35+0.25BL (1)
wherein BL represents the block ratio of the copolymer (I), and Wa represents the weight percentage, based on the total weight of the copolymer (I) and the resin (II), of the copolymer (I).