PURPOSE: to obtain good characteristics with a simple circuit constitution, by combinating the simple analog circuit with the operation circuit of the program control, in the multi-frequency receiver for telephone delivery system.

CONSTITUTION: The low pass filter 203 and high pass filter 204 separating the input multi-frequency signal into the frequency group including only one frequency respectively are provided, and the level detection circuits 206 and 211 detecting the output signal level of the filters 203 and 204 are provided. Further, the comparison circuits 208 and 213 comparing the output signal of the filters 203 and 204 with that of the circuits 206 and 211 and outputting the rectangular waveform, and the operation circuit 215 of program control inputting the rectangular waveform from the circuits 208 and 213 and output circuit 220 are provided. The circuit 215 is connected with the operation clock generation circuit 216 and the read only memory 218, the counter advanced every given time with the program is provided in the circuit 215, and the time length of the predetermined period of rectangular waveform is measured and the intput multi-frequency signal is judged from the result.