To obtain a composition useful for the production of piping materials excellent in tensile strength and pulsating hydraulic pressure strength by composing it of a vinyl chloride-based resin and a powdery alkyl tin mercapto-type stabilizer each in a specific amount.

This composition comprises 100 pts.wt. of a vinyl chloride-based resin (e.g. PVC) preferably having an average polymerization degree of 400-1,400 and 0.3-10 pts.wt. of a powdery alkyl tin mercapto-type stabilizer represented by the formula. In the formula, R is a 1-12C linear or branched alkyl; (m) is 1-2; and (n) is 1-10. It if required, there are further admixed 0.5-8 pts.wt. of an MBS type resin comprising a grafted polymer obtained by the graft polymerization of acrylic monomers such as methyl methacrylate and the like, acrylonitrile type monomers and styrenic monomers and the like onto the rubbery resin such as polybutadienes, styrene-butadiene-based rubbers and the like, the rubbery resin ingredient constituting at least 60 wt.% of the resin.