PURPOSE: To prevent a processor from increasing in scale and to easily perform speech recognition for the input of a transmission line side by finding a common processing between a speech encoding part and a speech recognition part and a common processing between a speech synthesis part and a speech decoding part, and simplifying them.

CONSTITUTION: The speech processing system consists of a speech input part 200, the speech encoding part 210, the speech decoding part 230, a speech output part 240, a speech recognition processing part 220, and switches S1, S2, and S3. The speech input part 200 consists of a gain correcting circuit 201, an LPF 202, and an A/D converter 203. The speech encoding part 210 consists of a short-period predictive analysis part 211, a sound source estimation part 212, and an encoding part 213. The speech decoding part 230 consists of a decoding part 231, a sound source reproduction part 232, and a synthesis part 233. The speech output part 240 consists of a D/A converter 241, an LPF 242, and a gain correcting circuit 243. The speech recognition processing part 220 consists of a speech recognition part 222, a control part 223, a speech code generation part 224, and a storage circuit 225.