PURPOSE: To make encoding which ensures secrecy to a requisite and sufficient degree in a short processing time when the encoded voice information is to be decoded.

CONSTITUTION: From voice information given by a microphone 1, a DSP part 5 produces encoding information including the linearity prediction factor and sound source information data, and supplies the produced information to a main control circuit 8. In this main control circuit 8, a plurality of data tables are stored which contain the data for rearrangement in a data table storing part 8A formed internally. On data table is selected according to the encoding data set previously through combining of operating button(s) and switch(es), and thereupon among the encoding information given by the DSP part 5, at least the linearity prediction factor and the sound source gain data among sound source information data are converted so that the encoded information is produced.