PURPOSE: To accurately inspect the phase of the power circuit of a motor by providing a current transformer capable of gripping an electric wire from the outside to supply or cut off the DC between the phases of a three-phase circuit and judging the order of induced spike like currents.

CONSTITUTION: The switches A, B of a current applying device 11 are operated to supply and cut off the DC between the phases of a three-phase circuit consisting of lead wires 12, terminal stands 6, cables 7, connection parts 10, draw-out wires 9 and a motor 8. The grips CT 17 of a judge device 15 can catch the change of the DC allowed to flow by an applying device 11 to induce spike like currents at the times of the supply and cut-off of the DC. The electric signals detected by the grips CT 17 are inputted to an input order judge part through lead wires 16 and the order thereof is judged. The judge result is displayed on an input order display part 20 at every phase and a phase correct- or-not judge part judges whether a phase is correct or not and, therefore, accurate inspection can be performed.