If a power supply path is in an abnormal state, a power-supply-path protection circuit of a power supply controller inhibits a switching circuit that switches on/off power supply from a power source to a load from power supply, using data related to a protection-current temperature characteristic line set by a characteristic setting circuit. The protection-current temperature characteristic line has a characteristic in which a protection current value is constant corresponding to increase in an ambient temperature or a negative characteristic in which the protection current value reduces corresponding to increase in the ambient temperature. Within a temperature range equal to or lower than an supposed maximum ambient temperature around the power-supply-path, the protection-current temperature characteristic line and a power-supply-path temperature characteristic line have a relation that the protection-current value is equal to or lower than an allowable current value at an identical ambient temperature.