A control system includes an encoder and a control device that controls a target object by using information transmitted from the encoder by serial communication. The encoder includes a position information generating unit that generates position information made of a predetermined amount of data and including absolute position data of an object to be detected; a configuration information generating unit that generates configuration information representing a ratio of the absolute position data in the amount of data during serial communication; and a transmission unit that transmits, to the control device, the position information and the configuration information as a series of serial data. The control device includes a reception unit that receives the position information and the configuration information transmitted from the encoder; and a control unit that processes the position information received by the reception unit on the basis of the configuration information received by the reception unit.