Abstract: The acceleration/deceleration control apparatus using slip speed detects an angular frequency .omega.r corresponding to an execution speed of an induction motor and derives an angular frequency .omega.s corresponding to a slip speed corresponding to a slip speed in response to a torque of the said motor, from a vector controller of the said motor.On the other hand, an allowable value .omega.s' of said angular frequency corresponding to the said .omega.r is prepared beforehand, and is compared with said angular frequency .omega.s.According to the result of this comparison, the IM rotation is controlled. So even if the induction motor is used as servo motor, no shock of the torque will flow through the motor and the motor itself will not be stalled.