To reduce power loss due to a thermistor element in a protection circuit for secondary battery.

The protection circuit for secondary battery includes a transistor 14 for current control whose source and drain are connected in series with a charging/discharging circuit 10b for a secondary battery 6; a thermistor element 20 connected with the gate of the transistor 14 for current control; and a resistor 24 for voltage regulation between the terminal 22 between the gate of the transistor 14 for current control and the thermistor element 20, and the source of the transistor 14 for current control. In the thermistor element, when temperature is normal, it brings the transistor 14 for current control into a state in which the transistor can be turned on, and, when the temperature abnormally rises, its resistance value is increased to bring the transistor 14 for current control into a state in which the transistor is turned off.