PURPOSE: To control the recovery time including a response as well as to carry out an input/output instruction for a peripheral LSI of an information processor against a high-speed operation of a CPU without correcting the program that controls directly the peripheral LSI of the information processor.

CONSTITUTION: When the input/output instruction givn to a peripheral LSI 14 is carried out by a program that controls directly the LSI 14, an input/output instruction monitoring part 3 transfers the input/output instruction to a recovery control program 4. Then a port address retrieving part 6 serving as a software module contained in the program 4 decides whether the recovery control is necessary or not. If necessary, a recovery time calculating part 8 carries out the input/output instruction by delaying the transmission of an output instruction signal so that a WAIT control part 11 controls the instruction issuing timing to the LSI 14 by an extent equal to the WAIT time shown as a difference between the counted time supplied from a time counting part 10 and the time set in the precedent access state and supplied from a port address recording part 13.