An object of the invention is to provide a damping material resin composition which is great in loss tangent, exhibits outstanding damping properties and enables a damping material to retain its own shape. The invention provides a damping material resin composition comprising 100 parts by weight of a thermoplastic resin having a chlorine content of 20 to 70 wt. % and a weight average molecular weight of at least 400,000, and 100 to 1000 parts by weight of a chlorinated paraffin having a chlorine content of 30 to 75 wt. % and 12 to 50 carbon atoms. (Preferably, the chlorinated paraffin contains 10 to 70 wt. % of a chlorinated paraffin having a chlorine content of at least 70 wt. %.)