To assist an audience in understanding the contents of reading by adding a reading speed, a rhythm and an emotional tone to the sound of a synthesizing speech to be read out.

Regarding a speech synthesizing device where a text is linguistically analyzed as a word, a rhythm is generated in the reading of the word, and a speech waveform is generated for the text for synthesizing a speech, an important part specifying part 11 for specifying an important part in the linguistically analyzed text and an important part rhythm part 12 for generating a rhythm for keeping the important part speed by the important part specifying part 11, different from parts other than the important part in the text are provided, together with an important part generation part 13 for generating a speech waveform for the important part.