To suppress intensive transmission of control information and suppress missing of a packet and rise in load of a device.

As one embodiment of this invention, an environment control system has a plurality of measurement nodes, a plurality of control nodes, and a control device and controls the environment condition in a room, each of the plurality of measurement nodes performs measurement of a factor changing the environment condition of the room and broadcasts a result of the measurement to a network, each of the plurality of control nodes affects the environment condition of the room according to control information transmitted from the control device, and the control device receives the result of the measurement broadcasted from the plurality of measurement nodes, compares it with a set environment condition of the room, and disperses a plurality of numbers of control information within a predetermined time and transmits them when transmitting the plurality of numbers of control information within the predetermined time to the plurality of control nodes in accordance with results of the comparison.