Abstract: In a control apparatus including a main control section and a plurality of remote PLC devices each connected to the main control section, the main control section has a PLC computing unit controlling the entire system and a remote PLC communication control section executing data transaction via a communication line with the plurality of remote PLC devices, and each remote PLC device including a communication control section executing data transaction via a communication line with the main control section, a memory section for storing therein a sequence program transmitted through the communication line and specified to the remote PLC device, a machine input/output I/F section for executing data transaction with external machine controlled by the remote PLC device, and a PLC computing section for executing PLC processing according to a sequence program and based at least on data transmitted from the main control section and data obtained from the machine input/output I/F section.