In a system for carrying out a program to be tested, an interrupt generator is provided; this program includes a plurality of routines designed to be called and executed in a predetermined order. The interrupt generator generates an interrupt request every time one of the plurality of routines is called. A determining unit is provided in the system. The determining unit determines whether a sequence of instructions in the program is normal based on historical information indicative of whether the interrupt request corresponding to at least one of the plurality of routines is generated.