A soft thermoplastic resin composition comprising:100 parts by weight of a resin component (A) containing 15 to 65 parts by weight of a vinyl chloride resin having a degree of polymerization of 2000 or less, and 35 to 85 parts by weight of a polyhydroxyalkanoate; and 0.1 to 8 parts by weight of a resin component (B) which is one or more resins selected from the group consisting of a (meth)acrylate resin and an acrylonitrile-styrene resin, and has a weight average molecular weight, in terms of the polystyrene, of 400,000 or more.