PURPOSE: To prevent a reluctant access unable state at the user side of a file system by cutting off a power supply if it is decided that the file system of its own computer is not offered to another computer.

CONSTITUTION: A file system offer deciding means 104 decides whether the file system of its own computer is offered to another computer or not based on the file system offer information if the cut-off of a power supply is requested by a request control means 101. If so, the power cut-off request is held. If not, a power cut-off means 105 cuts off the power supply. Thus a reluctant access enable state can be avoided to a file within a file system at the user side of the system.