In a copy control method, during a process for the acquisition of a data copy at a designated time, a recovery period of time can still be reduced when an input/output request is issued for copy source data at the designated time. For a system that includes a first storage device in which data are stored, a second storage device that obtains a data copy, and a host computer that writes data to the first storage device, the second storage device obtains blank input/output requests that are issued at predetermined time intervals if the host computer does not generate an input/output request for the first storage device, and the second storage device determines that a time closest to a predetermined data copy acquisition time, which is a target time for the acquisition of a data copy, is a copy execution time for the acquisition of a data copy.