1. A language model creation device comprising: a language model creating unit configured to execute a language model creation process of: acquiring a first content-specific language model which represents an appearance probability that a specific word appears in a first content, the first content comprising a first word sequence, a second content-specific language model which represents an appearance probability that the specific word appears in a second content, the second content comprising a second word sequence, a first probability parameter representing a probability that a content represented by a target word sequence is the first content, and a second probability parameter representing a probability that the content represented by the target word sequence is the second content, the target word sequence being at least a part of a speech recognition hypothesis generated in a speech recognition process; and creating a language model based on the first probability parameter, the second probability parameter, the first content-specific language model and the second content-specific language model, the created language model representing a combined appearance probability which is a probability that the specific word appears within at least a portion of the target word sequence.