PURPOSE: To improve a workability in assembling of a heater to complete it by a method wherein some heater elements are passed through a heater element fixing fitting at one side and the heater elements can be slid.

CONSTITUTION: A fixing fitting 10 at one side is fixed to a top plate 1 of a heater through an insulator material 2 by a screw 4. Some heater element 5 are passed through the holes made in the fixing fitting 10. One of the fixing fittings 11 is fixed to the top plate 1 of the heater through an insulator material 2 by a screw 4. The heater elements 5 are fixed to the fixing fitting 11 by fixing fittings 6 and a screw 7. The heater elements 5 are slid in the holes in the fixing fitting 10, thereby the heater elements 5 are extended without moving the positions of the fixing fitting 10 and the fixing fittings 11, resulting in that no irregular sound is generated and a reliability of completing of the heater is also improved.