POWER SOURCE CIRCUIT AND BATTERY CONTROLLER

PROBLEM TO BE SOLVED: To provide a power source circuit the power loss of which can be reduced, and a battery controller for a battery to which the power source circuit is applied. SOLUTION: In a power source circuit in which the source of an N-channel FET 22 is connected to the positive electrode of a power source 21, and the drain of another N-channel FET 23 is connected to the drain of the FET 22. The source of the FET 23 is used as the positive electrode of the power source 21, and the FETs 22 and 23 are turned on by boosting the voltages impressed upon the gates of the FETs 22 and 23 by operating a boosting circuit 26 when power supply is made, and turned off by stopping the operation of the boosting circuit 26, when the power supply is not being supplied. Therefore, the power loss of the power source circuit can be reduced, while flowing-in currents are prevented by means of a parasitic diode 22a.