A control system has a control device for performing a control of a predetermined process, and a communication device for communicating with the control device. The control device has a first transmission unit for transmitting a request signal requesting for transmission of a response signal to the communication device, a first reception unit for receiving the response signal transmitted through a predetermined procedure from the communication device in response to the request signal transmitted by the first transmission unit, an authentication unit for performing authentication of the communication device using identification information of the communication device contained in the response signal received by the first reception unit and identification information of the communication device registered in advance, and a process executing unit for executing the predetermined process when the authentication of the communication device by the authentication unit is successful. The communication device has a first storage unit for storing transmission scheduled time information indicating a time scheduled to transmit the response signal assigned to the communication device, a second reception unit for receiving the request signal transmitted from the first transmission unit, and a second transmission unit for transmitting the response signal corresponding to the request signal received by the second reception unit to the control device at a time different from times assigned to other communication devices based on the transmission scheduled time information stored in the first storage unit.