To provide a control device capable of reducing the number of wiring for connecting a detecting portion and a control portion, and the number of input terminals of the control portion.

A control device includes an encoder 3 for outputting detection signals of a plurality of phases which have different phases; and a control portion 11 for detecting a rotating direction and a rotation amount of an actuating portion rotating with the encoder 3, on the basis of the phases of detection signals x1, x2. The control device also includes a first conversion circuit 12 provided between the encoder 3 and the control portion 11, and converting the detection signals of the plurality of phases into a first conversion signal x3; and a conversion table 16 provided on the control portion 11, and calculating the rotating direction and the rotation amount of the actuating portion on the basis of the first conversion signal x3.