PURPOSE: A thermoplastic rubber composition having low compression set and improved weather resistance, requiring no vulcanization, comprising a chlorusulfonated polyolefin containing a gelatinous component, a vinyl chloride resin and a plasticizer.

CONSTITUTION: (A) A chlorosulfonated polyolefin having preferably 20W50wt% chlorine content, especially one having ≥10wt%, preferably 30W98% toluene- isoluble gelationous content obtained by subjecting chlorosulfonated polyethylene to intermolecular crosslinking by after-treatment reaction with peroxide is blended with (B) a vinyl chloride resin having 50W5,000 average polymerization degree in a ratio of the component A:B of 0.5:9.5W9:1, preferably 1:9W8:2 and (C) preferably 20W300pts.wt. based on 100pts.wt. component B of a plasticizer such as di-2-ethylhexyl phthalate, etc., to give the aimed composition.