Enables symbol insertion evaluation in consideration of a difference in speaking style features between speakers. For a word sequence transcribing voice information, the symbol insertion likelihood calculation means 113 obtains a symbol insertion likelihood for each of a plurality of symbol insertion models supplied for different speaking style features. The speaking style feature similarity calculation means 112 obtains a similarity between the speaking style feature of the word sequence and the plurality of speaking style feature models. The symbol insertion evaluation means 114 weights the symbol insertion likelihood obtained for the word sequence by each of the plurality of symbol insertion models according to the similarity between the speaking style feature of the word sequence and the plurality of speaking style feature models and the relevance between the symbol insertion model and the speaking style feature model, and performs symbol insertion evaluation to the word sequence.