To reduce the initial investment to promote widespread use of an automatic charge collection system by eliminating the need for separately purchasing an on-vehicle device usable in the system and mounting the device on a vehicle.

The portable communications terminal 3 owned by a user in a vehicle, on receiving a polling signal from an entrance (exit) processing machine which performs the process of collecting charges from vehicles passing through it, shifts to an ETC on-vehicle device mode in which the terminal communicates with the entrance (exit) processing machine. By making radio communications with the processing machine in the ETC on-vehicle device mode, the process required when a vehicle passes through a gate is carried out.