A program monitoring method includes the steps of describing an operating point code (2P) indicating an operating point value (3P) in one or more locations of a module (1M), counting the operating point value (3P) indicated by the operating point code (2P) by a counter if an execution position becomes the location of the operating point code (2P) while the module (1M) is being executed, and deciding that the module (1M) has not been executed normally if a difference between the numerical value counted by the counter and a score value (3S) is not a predetermined numerical value.