PURPOSE: To provide a variable rate transmitter whose circuit scale is small by generating the clocks of a frequency corresponding to a transmission speed and providing plural low-pass filters provided with a cut-off frequency corresponding to the transmission rate.

CONSTITUTION: A clock generation circuit 2 generates the clocks of the frequency corresponding to the transmission rate of data and a waveform data generation circuit 3 generates digital waveform data band-limited by a sampling frequency corresponding to the transmission rate for transmission digital data inputted from a terminal 1. The digital data are converted to analog sample value signals by a D/A converter 4 and return back noise is eliminated by the plural kinds of analog low-pass filters 5 and 6. The filters are provided with the cut-off frequency corresponding to the transmission rate, changeover is performed in a switch 7 according to the transmission rate and output the result to the terminal 8. The waveform data generation circuit 3 and the D/A converter 4 are respectively constituted of one piece and the circuit scale is made small.