To eliminate adverse influences on lines, realize downsizing and low cost and reliable detection of an overcurrent protecting operation state by a positive temperature characteristic thermistor element.

This overcurrent protecting part includes a positive temperature characteristic thermistor element for current limitation, having a positive temperature characteristic thermistor element body 1 and internal electrodes 2 and 3 for current circuit formed on both surfaces of the element body 1, and also includes positive characteristic, temperature-sensitive thermistor element having a positive thermistor element body 5 and internal electrodes 6 and 6 for resistance value detection formed on one of surfaces of the element body 5, the both thermistor elements being thermally coupled with each other. The overcurrent protecting part detects the overcurrent protecting operation state, on the basis of a resistive value of the temperature-sensitive thermistor element.