A virtual storage control apparatus of the present invention writes data of a write request in an empty block of a virtual disk for data integrity to which any malicious access or false operation is not made, and records the time and the way of rewriting the data into the virtual disk by the write request on a rewrite information storage unit. When there is a data restore request for the virtual disk by designating a virtual disk and write time, the virtual storage control apparatus reads the data of the virtual disk at the write time from a virtual disk for data integrity, based on the information in the rewrite information storage unit, and restores the data of the virtual disk at the write time. With this configuration, the integrity of the data updated successively with the passage of time can be implemented.