A control system, comprising: a plurality of control devices connected to a first network, and one or more equipment connected to each of the plurality of control devices via a second network; characterized in that each of the plurality of control devices comprises: an upper communication part which transmits/receives first data to/from other control devices via the first network, and a lower communication part which transmits/receives second data to/from the one or more equipment via the second network; the upper communication part has a first timer time-synchronized with each other among the plurality of control devices, and the lower communication part determines, based on the time of the first timer, a timing to start processing for transmitting the second data to the one or more equipment, wherein the upper communication part determines a timing to start processing for transmitting the first data, based on a maximum value of the time required for transmission/reception of the second data by the lower communication part in each of the plurality of control devices with reference to the timing to start processing for transmitting the second data. a plurality of control devices connected to a first network, and one or more equipment connected to each of the plurality of control devices via a second network; characterized in that each of the plurality of control devices comprises: an upper communication part which transmits/receives first data to/from other control devices via the first network, and a lower communication part which transmits/receives second data to/from the one or more equipment via the second network; the upper communication part has a first timer time-synchronized with each other among the plurality of control devices, and the lower communication part determines, based on the time of the first timer, a timing to start processing for transmitting the second data to the one or more equipment, wherein the upper communication part determines a timing to start processing for transmitting the first data, based on a maximum value of the time required for transmission/reception of the second data by the lower communication part in each of the plurality of control devices with reference to the timing to start processing for transmitting the second data. an upper communication part which transmits/receives first data to/from other control devices via the first network, and a lower communication part which transmits/receives second data to/from the one or more equipment via the second network; the upper communication part has a first timer time-synchronized with each other among the plurality of control devices, and the lower communication part determines, based on the time of the first timer, a timing to start processing for transmitting the second data to the one or more equipment, wherein the upper communication part determines a timing to start processing for transmitting the first data, based on a maximum value of the time required for transmission/reception of the second data by the lower communication part in each of the plurality of control devices with reference to the timing to start processing for transmitting the second data.