To quickly stop a state that the power consumption of a communication card is increased when the communication control means of a communication card run out of control.

When it is detected that a communication controller 4 runs away due to some reason, a communication card 2 switches an STSCHG signal from a high level to a low level. A host 3 detects that the STSCHG signal is switched from the high level to the low level during the supply of an operation power from an operating power supply part 10 for a communication card to the communication controller 4, and when it is detected that the change of the STSCHG signal is due to the runaway of the communication controller 4, the host 3 stops the supply of the operating power from the power supply part 10 for the communication card to the communication controller 4.