PURPOSE: To abolish the use of a clamping bolt and thin the thickness of a frame by a method wherein a belt-type thin sheet or a wire is wound more than 1 round around the outer periphery of the frame, pinching the heat transfer plate of a plate-type heat exchanger, to fix the heat exchanger.

CONSTITUTION: A belt-type thin sheet 10 is wound one round around the outer periphery of a pair of frames 4, 4, pinching the assembled body of heat transfer plates 2, and the starting end of the thin sheet 10 is fixed to the final end of the same by welding 12. According to this method, a load, concentrated on respective bolts in case the heat transfer plates are clamped by the bolts, is distributed uniformly on the widthwise direction of the thin sheet 10 to obtain an equally distributed load. As a result, the frame 4 is deflected into X-direction only, therefore, thinner frame 4 can be used compared with the case of clamping effected by the bolts.