Abstract: A transmitting apparatus based on phase modulation including a data encoding circuit (100), a phase locus control circuit (200) and a modulator (300). The data encoding circuit (100) divides input data to be transmitted into a predetermined number of bits, and sequentially outputs them as segmented data. The phase locus control circuit (200) outputs a phase locus control signal representing each of the segmented data by three values of a positive direction, a negative direction and a non-rotation state of the phase rotation. The modulator (300) changes the phase of a transmission signal in response to the phase locus control signal. Using the phase rotation direction information of the three values makes it possible to reduce transmission bits, to increase transmission speed and transmission capacity.