A heat-resistant ultrasonic sensor forms a piezo-electric ceramics film with a thickness of 0.5 mm or smaller and a Curie point of 200° C. or higher on a flexible metal plate. A thin metal film that is an electrode is attached to a top surface of the piezo-electric ceramics film and a metal wire mesh covers the thin metal film and is attached to a top surface of the thin metal film. A core of a heat-resistant coaxial cable is connected to the metal wire mesh at a connection point. The heat-resistant coaxial cable is fixed to the thin metal plate with a metal fixing member that is a ground portion. An electric insulating cover is attached to the thin metal plate and covers the piezo-electric ceramics film, the thin metal film, the metal wire mesh, the connection point, the fixing member, and the core of the coaxial cable.