PURPOSE: To highly reliably exchange information at a high speed between the main body of portable electronic equipment and a charging type battery which becomes the power source of the equipment.

CONSTITUTION: A light emitting element 7a and light receiving element 8a are arranged in the main body 1 of a portable telephone set and another light receiving element 8b and light emitting element 7b are provided at the positions corresponding to the light emitting and receiving elements 7a and 7b in a battery pack 4 incorporated with a charging type battery 5. The light emitting element 7a in the main body 1 outputs a control signal which controls the circuit of the battery pack 4 and the light receiving element 8b of the pack 4 receives the signal. The light emitting element 7b of the pack 4, on the other hand, outputs information on the voltage, remaining usable time, etc., of a battery and the light receiving element 8a in the main body 1 receives the information. Therefore, the information can be exchanged between the elements highly reliably at a high speed. In addition, the degree of freedom in the design of the equipment can be increased and the size of the equipment can be reduced further, because the degree of freedom in the arrangement of the light emitting and receiving elements can be increased.