To provide a communication sequence by which communication can stably be carried out even with a slow CPU in order to realize a wireless network node of a long communication distance and a long battery life.

In the case of changing the characteristic number of the wireless network node by radio from a master set to the wireless network node, the master set transmits the characteristic number of the wireless network node to the wireless network node, and the wireless network node transmits completion of preparation for changing the characteristic number when receiving its own characteristic number to the master set. The master set sends a changed characteristic number to the wireless network node again, and the wireless network node having received it changes its own characteristic number. Such a sequence is carried out by this wireless network node system.