To solve the problem that effective utilization of adhesive strength cannot be achieved resulting from a delay in the estimation of a torque corresponding to a tangential force between wheels and rails in one pulse mode of an inverter for driving a main motor.

If driving wheels are still in the middle of re-adhesion or do not go toward the re-adhesion at the point of time when a command of the minimum value of a torque command value calculated from an estimated torque corresponding to the tangential force for a predetermined period is finished in detecting idling/sliding operations during the one pulse mode of the inverter, the torque smaller than a torque command value till then is commanded for re-adhesion. Then, the torque obtained by correcting a torque command predetermined value calculated at the point of detection of the idling/sliding operations to a little smaller value is commanded. The subsequent stock speed is calculated from an average acceleration/deceleration during the period when the corrected torque is commanded, and when a difference speed between an estimated stock speed and a driving wheel speed reaches at least a threshold, the idling/sliding is detected so that they may re-adhere to each other without fail while the speed of the idling/sliding is being restrained from increasing.

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