To prevent rupture by pushing a deformed steel bar in the longitudinal direction without forming projecting sections by deforming working to outer circumferences at both end sections of the deformed steel bar and forming header sections at both end sections in the deformed steel bar with projecting sections by deforming working.

In the deformed steel bar 1 with an end section 2, in which there is no deforming working, deforming working is executed to sections excepting the end section 2 or deforming working is executed to the whole surface of the steel bar, and a projecting section by deforming working is removed by cutting, etc., only at the end section. When the diameter of the smoothed steel bar 1 is represented by 2R and the length of a smoothed section by L, L/2R>1.5 or L/2R<4 holds at the ratio of the length L to the diameter 2R for molding a heater most effectively. The deformed steel bar 1 with a header section 3 is molded by pushing the longitudinal direction of the steel bar 1 by the deformed steel bar 1 with the end section 2, in which there is no deforming working. Accordingly, working to an end plate and the mounting process of the steel bar are simplified while large prestress can be imparted.