A migration-destination primary storage apparatus (MD-PDKC) comprises a second PVOL and a second journal storage area storing a journal corresponding to write data for the second PVOL, and executes a data copy to the second PVOL from a first PVOL, which is in a migration-source primary storage apparatus (MS-PDKC) and forms a copy pair with an SVOL in a secondary storage apparatus (SDKC). After the data copy has been completed, the MD-PDKC acquires the latest write sequence information from the MS-PDKC, and upon receiving a write request for the second PVOL, writes the write-request write data to the second PVOL, creates a journal by using journal data corresponding to the write data and also by using update information showing write sequence information based on the acquired latest write sequence information, and writes the journal to the second journal storage area.