A method of controlling the drive force to be applied to the load that is driven with a servo motor, wherein the control error that is caused by the change in the condition of a transmission mechanism interposed between the servo motor and the load is decreased. A detected value (PH) of the drive force actually applied to the load is compared with a set value (PL') to be applied to the load, and a drive current of the servo motor is controlled depending upon the result of comparison. When the condition of the transmission mechanism is changed, therefore, a change in the relationship between the servo motor output and the drive force actually applied to the load is automatically compensated, so that the drive force to be applied to the load is properly controlled to assume a set value.