A semiconductor storage device, includes a plurality of flash memories and a controller for the flash memories. The flash memory includes a data cache operable to hold data for at least one record page in writing, the flash memory includes a plurality of erasure blocks each having a plurality of record pages, the record page is classified into a first record page and a second record page of which write time is longer than a write time of the first record page, and the controller for the flash memories is configured to: divide the plurality of flash memories into at least two groups; perform write control by interleaving data in the groups for each record page; determine whether a page to be written data is of the first record page or the second record page; and when it is determined that the page to be written data is the first record page, after a lapse of a first predetermined time from start of writing data of one of the groups, the controller starts writing data of another one of the groups, and when it is determined that the page to be written data is the second record page, after a lapse of a second predetermined time being longer than the first predetermined time from start of writing data of one of the groups, the controller starts writing data of another one of the groups.