PURPOSE: To provide the buffer storage control system whose fetch access performance to a buffer storage device is improved.

CONSTITUTION: At the time of fetch access to a buffer storage device 3, in the case a buffer mishit is detected, a bypass fetch is executed unconditionally to a request origin 4 from one set of move-in register 2 selected arbitrarily, and data is sent out to the request origin 4. Thereafter, the move-in register for holding data of an address subjected to fetch request is specified, and simultaneously, success or failure of the bypass fetch is decided, and its result is reported to the request origin 4. In the case the bypass fetch executed unconditionally is unsuccessful, the fetch access is executed again, and the data is fetched from the move-in register 2 decided to be one which is requesting move-in to the same area as the fetch access to the main storage device 1.