PURPOSE: To obtain composite material for electret which is suitably used for an electrostatic type electroacoustic transducer such as a microphone and a head phone.

CONSTITUTION: In the manufacturing method of composite material for electret formed by thermo-comprssion bonding of a metal plate and a thermosetting resin film, a metal plate which is previously heated at (melting start temperature of a thermosetting resin film-50°C) to decomposition start temperature of the thermosetting resin film and the thermsetting resin film are continuously supplied between two rubber rolls, and thermo-compression bonding is performed. Further, after that, heating is again performed at the melting start temperature of the thermosetting resin film-the decomposition start temperature of the thermosetting resin film. Hence the composite material excellent in the flatness of film surface and the adhesion between layers can be effectively obtained.