SECONDARY BATTERY PROTECTION DEVICE

Device miniaturization is made possible by building a battery protection circuit in a microcomputer. A secondary battery protection device comprises a voltage detection means 7 that detects a voltage of a power supply circuit 6 including a secondary battery 1, a current detection means 8 that detects a current of the power supply circuit, and a battery protection circuit 10 that shuts off the power supply circuit 6 based on a signal representing a detection made by the voltage detection means 7 or the current detection means 8 of an excess current that is generated in the power supply circuit 6, wherein the protection circuit 10 is built in a microcomputer 13.