To provide a controller of a production apparatus, which can quickly stop a motor with a simple structure even if a fault occurs in a position detector.

The controller operates a dynamic brake (S5) at first if abnormality of the position detector is determined (S1:YES), and estimates a present electric angle θE of a servo motor from values of the respective phase currents of the servo motor, which are detected during a braking period, concretely, from a ratio of respective phase currents Iu, Iv and Iw (S6 to S9). When the dynamic brake is canceled, counter torque braking is performed in accordance with the estimated electric angle θE (S12).