It is an object of the present invention to provide a thermal transfer sheet which has a conductive primer layer having adequate adhesion and heat resistance without using a binder resin, has an excellent antistatic property, and hardly causes troubles in printing.The present invention pertains to a thermal transfer sheet formed by providing a thermally-transferable color material layer on one side of a substrate sheet and providing a heat resistant slipping layer on the other side of the substrate sheet with a primer layer interposed between the slipping layer and the substrate sheet, wherein the primer layer is formed by using a conductive colloidal inorganic pigment ultrafine particle.