PURPOSE: To prevent reoccurrence of a memory fault by discriminating a spreading range of a fixed fault, detaching its part from a system, and requesting retry to the system, at the time of intermittent fault.

CONSTITUTION: A fixed fault means 1 determines a parts name corresponding to a fault address from a fault spreading range pattern 31 stored in a local memory 30, and determines fault parts by executing a read check of the head address and the end address of its parts name. Subsequently, the fault address is subjected to read check by a fault classification discriminating means 10, and in the case a memory fault is not generated again, it is decided to be an intermittent fault, a retry request means 12 is actuated, and the retry request means 12 requests retry to an operating system 50, and thereafter, actuates an intermittent fault measuring means 13. The intermittent fault measuring means 13 determines the parts name corresponding to the fault address from the fault spreading range pattern 31, counts up the number of times of generated of the intermittent fault of the corresponding intermittent fault information 32, and thereafter, actuates an intermittent fault warning means 14.