1. A prosody generator comprising: a data dividing unit which divides into subspaces the data space of a learning database as an assembly of learning data indicative of the feature quantities of speech waveforms; a density information extracting unit which extracts density information indicative of the density state in terms of information quantity of the learning data in each of the subspaces divided by the data dividing unit, and a prosody information generating method selecting unit which selects either a first method or a second method as a prosody information generating method based on the density information, the first method involving generating the prosody information using a statistical technique, the second method involving generating the prosody information using rules based on heuristics.