A text-dependent voice authentication system that performs authentication by urging a user to input a keyword by voice includes: an input part (11) that receives a voice input of a keyword divided into a plurality of portions with an utterable unit being a minimum unit over a plurality of times at a time interval for each of the portions; registered speaker-specific syllable model DB (20) that previously stores a registered keyword of a user as a speaker model created in the utterable unit; a feature value conversion part (12) that obtains a feature value of a voice contained in a portion of the keyword received by each voice input in the input part (11) from the portion; a similarity calculation part (13) that obtains a similarity between the feature value and the speaker model; a keyword checking part (17) that determines whether or not voice inputs of all the syllables or phonemes configuring an entire registered keyword by the plurality of times of voice inputs, based on the similarity obtained in the similarity calculation part; and an authentication determination part (19) that determines whether to accept or reject authentication, based on a determination result in the keyword checking part and the similarity obtained in the similarity calculation part.