PURPOSE: To affect a file edited at a client computer separated from a network on a server computer after it is connected to the network.

CONSTITUTION: The file from a second computer B(server computer) 112 is stored in the file storage part 101 of a first computer A(client computer) 111 in advance. The file is edited in a state where the first computer A is separated from the network. When it is connected to the network again, a file copy control part 103 refers to a file information managing part 102, and compares storage time registered on the managing part with update time, and when it is judged that the time is updated, an updated file is copied on the second computer B112, and file edit performed at the first computer A while separation is being performed is affected on the second computer B 112.