PURPOSE: To make the recognizing of the fault of an apparatus by a user easy and improve the safety of the apparatus, by reporting the abnormality and defect of the power supply part of the apparatus to the user, and by making the re-operating of the apparatus impossible when the user does not perform such a treatment as resetting.

CONSTITUTION: When an apparatus is started by an operating switch 1, first, a cutting-off switch 12 is closed, and concurrently, by the opening of a load switch 5, a dummy resistor 2 is connected in series with a load 3. Thereby, the transient response of the apparatus is suppressed, and the voltage between points A, E is measured, and further, this voltage value is used as the initial value of an AC power supply voltage. Thereafter, the direct applying of the AC power supply voltage to the load 3 is performed by the closing of the load switch 5. The voltage present at this point of time between the points A, E is monitored at a fixed period, and when the value of this voltage is lowered, the apparatus is considered as an abnormal one, and after the opening of the cutting-off switch 12, a light emitting diode 6 is lit. These treatments are continued until a reset switch 8 is pushed by a user.