To provide a communication device having a function for adjusting a communication mode according to resources, such as capacity of power supply and power consumption, which the individual communication device is equipped with.

A communication device (Ac) is used in a communication system, in which operational conditions among communication devices driven by a battery are adjusted mutually and optimum communication setting is achieved as a whole. A power supply is subjected to management control through a power controlling unit (106). The operation of the whole communication system is controlled by a system control unit (103). The operation mode of the communication device (Ac) is subjected to setting control through an operation controlling unit (104). The operation of the whole system including the communication device is managed by a system control unit (105) according to the output of the power supply control unit (106).