A thermoplastic resin (A) including, in its main chain structure, a unit (i) having a biphenyl group, a unit (ii) having a substituent biphenyl group, a unit (iii) having a specific number of atoms in its main chain, and a unit (iv) having a specific number of atoms in its main chain provides a thermoplastic resin which has a low liquid crystal phase transition temperature and a low isotropic phase transition temperature, is highly thermally conductive, and can be processed by molding at a low melting temperature.