Provided is a thermoplastic polymer composition containing an aromatic vinyl-based block copolymer (a-1) having a number average molecular weight of 30,000 to 200,000, the aromatic vinyl-based block copolymer containing a polymer block F containing a structural unit derived from an aromatic vinyl-based monomer as a main component and a hydrogenated or non-hydrogenated polymer block G containing a structural unit derived from a conjugated diene monomer or an isobutylene monomer as a main component; an acrylic polymer (a-2); an olefin-based polymer containing polar groups (a-3); and a softening agent (a-4), at the proportions that satisfy the following Expressions (1) to (3): 0.05≤W(a-2)/W(a-1)≤9  (1) 0.1