PURPOSE: To obtain the speech rule synthesis device which can generate a fundamental frequency for generating a rule synthesized speech close to a natural speech that a human being voices.

CONSTITUTION: When information on the synthesized speech is inputted from an input part 101 to a rhythm parameter generation part 102, a fundamental frequency setting part included in the rhythm parameter generation part 102 sets the fundamental frequency from a specific arithmetic expression according to whether or not a precedent phrase directly relates with the corresponding phrase and whether or not the corresponding phrase directly relates with a following phrase by using a fundamental frequency setting rule dictionary and a speech parameter generation part 104 generates a speech parameter according to the set fundamental frequency; and a speech is synthesized by a speech synthesis part 106 and outputted from an output part 107.