To effectively prevent temperature drop due to heat loss near the exterior surface of a heating object part, raise precision and stabilize temperature control and further enhance energy saving, and to improve homogeneity in overall temperature distribution while reducing manhour related to the production process.

A temperature detector 1 of a molding machine M includes a temperature sensor 5 inserted in a sensor insertion hole 4 formed to a predetermined depth from the outer surface towards th inside of a heating object part 3 provided with a heater 2 and a cylindrical sensor holder 6 covering the temperature sensor 5. An aperture 7 communicating with the sensor insertion hole 4 through a region other than a heating element of the heater 2 from the outer surface 2bf of an attachment section 2b is provided on the attachment section 2b for attaching the heater 2 to the heating object part 3, the temperature sensor 5 is inserted to the insertion hole 4 via the aperture 7, and an end 6s of the sensor holder 6 is fixed directly or indirectly on the outer surface 2bf of the attachment section 2b.