PURPOSE: To simplify a system constitution and to eliminate a delay time by transmitting a corrected data to a requester when an error detecting circuit detects an error and at the same time correcting the data of a buffer storage with the address of the error data.

CONSTITUTION: The type of request given from a requester, an address, etc. are applied to a selecting circuit 1 from terminals A and B. Then the information selected by the circuit 1 is stored in an address register 2. The data of a buffer storage 6 is read out by the address and stored in a buffer storage register 7. In this case, the address of the register 2 is copied and held at an address register 3. At the same time, the data stored in the register 7 is transmitted to the requester from a terminal D as well as to an ECC circuit 8 which detects errors. When an error is detected, an error signal is transmitted to the requester. At the same time, the data of the storage 6 is corrected. Thus the constitution is simplified for an error processing system.