a speech synthesizing apparatus extracts small speech segments from a speech waveform as a prosody control target and adds inhibition information for inhibiting a predetermined prosody change process to a selected small speech segment in executing prosody control . prosody control is performed by performing a predetermined prosody change process by using small speech segments of the extracted small speech segments other than small speech segments to which inhibition information is added . this makes it possible to prevent a deterioration in synthesized speech due to waveform editing operation .