An NFS server, an NFS server control program and an NFS control method can reduce the extended lock reacquisition period. The NFS server comprises a prior-to-restart lock acquiring client information recording section for recording the identifiers of the NFS clients that have acquired locks before a restart of the NFS server and the number of the first files that is the number of files for which locks have been acquired, a lock acquiring client information recording section for recording the identifiers of the NFS clients that have reacquired locks after the restart of the NFS server and the number of the second files that is the number of files for which lock have been reacquired and an NSM that ends the reception of any lock reacquisition request from any of the NFS clients when the number of the second files of all the NFS clients acquired by the prior-to-restart lock acquiring client information recording section becomes equal to the number of the first files.