PURPOSE: To easily detect the capacity and the full charging of a secondary battery at the time of constant voltage charging by storing a control voltage and identification information peculiar to a charging apparatus and carrying out charging voltage control based on the stored identification information at the time of next attachement.

CONSTITUTION: When a secondary battery 12 is attached to a charging apparatus 11, a charging control circuit 15 in the charging apparatus 11 reads identification information of the charging apparatus 11 out of a storage apparatus 13 provided in a pack of the battery 12. If the identification information is not of own apparatus, the charging apparatus 11 does not carry out constant voltage control and raises the charging voltage gradually. An overvoltage detecting circuit 14 detects the overvoltage, the circuit 15 reads the overvoltage detected signal out of the circuit 14 and detects the output voltage at that time to compute control voltage. The identification information of own apparatus and the control voltage are sent to the battery 12 and written in the apparatus 13. If the identification information is of own apparatus, the circuit 15 reads the control voltage out of the apparatus 13 and carries out constant voltage control at the time of charging based on the received value.