To provide a polyamideimide resin composition suitable for a back- coating agent for a thermal transfer ribbon, a magnetic tape or the like, excellent in heat resistance and imparting a durable slipping property, to provide a varnish thereof and a manufacturing method of the varnish.

The polyamideimide resin composition comprises a silicone of general formula (1) (wherein R, R' and R" are each an alkyl group or an aryl group; and X is an alkyl or aryl group bearing at least two functional groups such as a hydroxyl group, a carboxyl group, an amino group and the like). The polyamideimide resin has heat resistance, abrasion resistance and a persistent slipping property, and is widely applicable to a back-coating material for a thermal transfer ribbon and a magnetic tape, a topcoat for a thermal recording material and other coating agents for various processed plastic articles, and the like. There are also provided a varnish of the polyamideimide resin and a manufacturing method of the varnish.