An operation control method to be implemented by each of a plurality of communication devices two-dimensionally arranged on a two dimensional diffusive signal-transmission board, each of the plurality of communication devices being configured to communicate by transmitting a transmission signal carrying data to another of the plurality of the communication devices using a two dimensional diffusive signal-transmission technology, the method includes judging whether a communication device being operated in a normal mode satisfies a predetermined condition, and setting the communication device into one of a low electrical power consumption mode in which at least one function is decreased, and a power off mode in which electrical power supply to the communication device is shut off, when the communication device being operated in the normal mode satisfies the predetermined condition.