PURPOSE: To provide a charger in which reliability is improved by reducing the number of connecting terminals and the secondary battery can be downsized.

CONSTITUTION: A battery pack 111 is connected at a first, terminal thereof with the positive pole of a secondary battery body 101 while at a second terminal thereof with the negative pole of the secondary battery body and one of the third or fourth terminal is connected with the positive or negative pole of the battery body 101 while the other of the third or fourth terminal is connected with one end of a temperature sensitive resistor element 102. Combination of connection is detected through a battery identifying section 105 while the type of battery is detected at the terminal position of positive or negative polarity of the battery. Voltage data are passed from remaining terminals to a temperature detecting section 106 where the temperature of the battery body 101 is detected. A charging current determining section 107 determines a charging current value based on these data and a charging current control circuit 108 controls charging of the battery body 101 based on thus determined charging current value.