To enable simplification of assembling a protection circuit board, while enabling to enhance downsizing of the protection circuit board.

This device is constituted of a frame body 60 having a first support member 70, a second support member 72, and a coupling member 74 for coupling between the respective support members 70, 72, a first wiring conductor 62 which is arranged on the first support member 70 of the surface side of this frame body 60 to constitute a first contact 78 and which also constitutes a first mounting terminal 80 by being extended via a side face of the first support member 70, a second wiring conductor 64 which is arranged on the second support member 72 of the surface side of the frame body 60 to constitute a second contact 82 and which constitutes a second mounting terminal 84 by being extended via a side face of the second support member 72, and a bi-metal switch 66 which is arranged straddling over the first contact 78 and the second contact 82, and which switches off between respective contacts 78, 82 in the case heated by the heater, while the recessed part 76 formed on the rear face side of the coupling member 74 is made to be an open state enabling the heater to be arranged.