The present invention provides a radio communication system in which not only a communication unit operating in a slave mode but also a communication unit operating in a master mode can be changed into a power saving mode.Among a plurality of communication units, one of them is operating in the master mode while the others are operating in the slave mode. Only the communication units operating in the slave mode are allowed to be changed into a suspend state. The communication unit operating in the master mode stops transmission/reception in synchronization with transition into the stop state of the communication units operating in the slave mode.