A crawler type power shovel vehicle (1) operated by a hydraulic actuator (20), constructed from an electric motor (31) for driving a hydraulic pump (32) for supplying hydraulic oil to the hydraulic actuator (20), a battery (50) for supplying direct current power, an inverter (41) for operating the electric motor (31) by converting the direct current power into alternating current power and supplying it to the motor, a controller (40) for causing the inverter (41) to control operation of the electric motor (31), and a voltage/current sensor (42) for detecting the magnitude of a load current flowing from the battery (50) into the inverter (41). The controller (40) stops the motor (31) when the magnitude of the load current detected by the voltage/current sensor (42) continuously exceeds a predetermined threshold for a predetermined time period.