PURPOSE: To provide an information processing system which can surely report the generation of a power supply fault in the system to a maintenance center.

CONSTITUTION: This system is provided with a magnetic tape controller 1 equipped with a control logic part 4, a power source part 7, a power source control circuit 6 provided with a power source ON/OFF control circuit 9 and a control power source 10 so as to control the power source part 7, and communication adapter 5 connected through a communication channel 20 to an external maintenance center 3. A power source 8 dedicated for the communication adapter and the control power source 10 independent of the power source part 7 are provided on the communication adapter 5 and the power source control circuit 6, a power supply voltage line 17 and a power supply abnormality report line 23 are provided between the power source part 7 and the power source control circuit 6, and a power supply alarm signal line 16 for transmitting the abnormality of the power source part 7 to the communication adapter 5 is provided between the communication adapter 5 and the power source control circuit 6. Then, the abnormality such as power supply interruption at the power source part 7 is reported from the communication adapter 5 through the communication channel 20 to the maintenance center 20.