A motor control unit 107 that controls a drive device 100 of a brushless DC motor 101 of a compressor 12 in a refrigerator 1 determines that a flammable refrigerant is not leaking when it is determined that a duty variation width A(t) of a duty value D(t) detected at a detection time t exceeds a reference duty variation width Aa of a duty value D(t0) measured at a duty measurement reference time t0 and a voltage value time rate-of-change ΔV of a voltage value V(t) of direct-current power exceeds a reference rate-of-change ΔVa.