To provide a heat resistant polyamideimide resin which enables to form a coating film and a seamless tubular body excellent in tensile strength and rupture elongation, and a seamless tubular body, a coating film, a coating film plate and a heat resistant coating material using the same.

The heat resistant polyamideimide resin is obtained by reacting (a) a polycarboxylic acid component including, as an essential component, a tri- or higher valent polycarboxylic acid anhydride having acid anhydride groups and carboxyl groups, (b) an imidodicarboxylic acid represented by general formula (I), (c) an aromatic diisocyanate represented by general formula (II), and (d) an aromatic polyisocyanate in a basic polar solvent. In the general formula (II), R1 and R2 independently denote H, alkyl, alkoxy or halogen. The coating material contains the heat resistant polyamideimide resin as a coating film component.