To provide an LSI having a low power mode that can prevent an apparatus on which the LSI is mounted from resulting in performance degradation, etc. even when its electric power is not reduced in the low power mode. Devised is a circuit that instructs an operation mode and detects whether the LSI operates as specified by the mode, and that measures a current at the time of the low power mode in a pseudo manner and, if despite having shifted to the low power mode, the current is not reduced actually, issues an alarm signal.