To remove a virus and to suppress an adverse effect to a system due to virus infection by periodically starting a virus checking program.

When receiving a start command from a starting means 11, a virus checking means 12 executes virus checking processing for detecting and removing a computer virus and a data sending means 12 sends virus detection data in detecting a computer virus or sends virus removal data in removing the computer virus. A detection message is prepared and outputted by message output means 15, 17, based on the virus detection data. On the other hand, a removal message is prepared and outputted based on the virus removal data and a history data memory 16 time-sequentially stores at least the contents of the messages out of the virus detection data and the virus removal data.