PURPOSE: To determine a deadlocked object job so as to reduce roll-back load and reprocessing load at the time of deadlock.

CONSTITUTION: An exclusive control means 1 which executes shared lock processing 11 to inform the job whose roll-back processing load is small of the deadlock at the time of the deadlock of a system sharing a buffer for file input/output, exclusive lock processing 12 to inform the job whose reprocessing load after roll-back is smaller of the deadlock at the time of the deadlock of the system not sharing the buffer for file input/output, and lock canceling processing 13 is provided. The throughput of multiple parallel processing is improved.