A data management server that can prevent data stored in a user's folder on the server from being used by others when the user is not working, even in a client-server network environment. The data management server that manages data that can be used by multiple terminal devices, and constitutes a storage device in which separate storage areas are allocated for each user. A determination unit determines which of the terminal devices is in a state in which it is able to access the data management server. When a terminal device issues a request to access a separate storage area of the storage device, if it is determined by the determination unit that the terminal device of a user associated with the separate storage area is in a state in which it can access the data management server, an access management unit permits the requesting terminal device to access the data stored in the separate storage area. If the associated user's terminal device is not in such a state, the access management unit denies access to the data stored in the separate storage area. In an alternative embodiment, limited access for certain types of processes may be permitted when the associated user's terminal device is not in the access-enabled state.