A communication apparatus using a synchronized clock signal includes: a communication signal generation unit generating one of a baseband signal and a signal obtained by applying digital modulation to the baseband signal, as a communication signal; an interface unit transmitting the generated communication signal and receiving a communication signal from an external source; a communication signal analyzing unit analyzing the received communication signal; a clock signal providing unit providing a clock signal to the communication signal generation unit, the interface unit, and the communication signal analyzing unit; and a controller controlling the communication signal generation unit, the interface unit, the communication signal analyzing unit, and the clock signal providing unit.