To reduce the power consumption in a reception standby state and at the same time, to receive an electronic mail in real time via a mobile object communication network such as a PHS communication network etc. in a portable personal computer provided with a communication function.

This personal computer is provided with a pager circuit block 35 provided with a pager function in addition to a PHS circuit block 35 provided with a function performing the transmission/reception with a PHS communication network. The PHS circuit block 30 is made a working state when the pager circuit block 35 detects an individual selection calling signal and further discriminates a PHS starting signal. Because the power consumption of the pager circuit block 35 is about 1/10 of the power consumed when the PHS circuit block 30 is in a reception standby state, the load of a battery can be reduced. Therefore, a processing continuously receiving an electronic mail for long time can be performed by a personal computer 10.