To stop excess-time conduction to a load device in an electric circuit device which selectively turn on electricity for a load device of which one round of operating time is limited to a short span of time.

On the way of a primary circuit 5 of a relay 2, a heat-generating means 8 generating heat through its conduction, a heat-sensing means 12 generating either thermal deformation or thermal degeneration after being heated by heat generated by the heat-generating means, and contact point means 9, 10 for opening up to break the primary circuit of the relay as at least either the thermal deformation or the thermal degeneration of the heat-sensing means progresses to a certain extent.