To provide a thrust increasing method of a vertical drive shaft by eliminating such defect as a drive torque and a working thrust cannot be increased since the vertical drive shaft is driven with a high lead ball screw and a linear motor.

In the vertical shaft control method of a working device including a vertical shaft body supporting a vertical drive shaft that is controlled by an adjusting mechanism of a counter balance, the drive direction of a vertical main shaft body, a deviation from a target position, or change in the drive current of a shaft drive motor are measured. An adjusting mechanism of a counter balance is controlled and the weight of the vertical main shaft body is utilized for drive torque and working thrust.