PURPOSE: To maintain stable recording quality by restraining generation of warp due to difference in thermal expansion coefficient between an insulating substrate and a radiating plate 1 of a thermal head and by radiating uniformly.

CONSTITUTION: A thermal head body consists of a radiating plate 1 and an insulating substrate 3 having a plurality of heat generating resistors 2 arranged in a line. At both ends of the insulating substrate 3, terminals 6 for supplying electric current to each of the heat generating resistors 2 are provided. The radiating plate 1 adheres to the insulating substrate 3 by a silicone rubber adhesive 4. The space between the radiating plate l and the insulating substrate 3 is coated with a silicone oil 5 for radiation. On the radiating plate 1, two grooves 7 are provided for preventing the radiating silicone coil 5 from intruding in between the adhesive 4 and the radiating plate 1. Overflow of the radiating silicone oil 5 at adhering is absorbed by the two grooves 7.