A code excited linear prediction type speech coder, which includes a seed storage that stores seeds used as an initial state of oscillation, and an oscillator that generates different vector sequences in accordance with values of the seeds stored in the seed storage and outputs the vector sequences as excitation vectors. The speech coder also includes a linear predictive coding synthesis filter that receives, as input, the excitation vectors, which are the vector sequences generated in accordance with the values of the seeds, that synthesizes the excitation vectors, and that outputs a synthesized speech.