To provide a device and a program for improving efficiency and convenience by omitting impractical calculation of word division.

A dictionary registering only words and a language model (N gram model) for imparting connection probability between words are stored in a word dividing device 50. A plurality of hypotheses of word division consisting of words registered in the dictionary are generated for an inputted Japanese text by a hypothesis generating/deleting part 30. A product of the connection probability between words in the hypotheses is calculated based on the language model by a hypothesis calculating part 20. Words are merged such that only a hypothesis in which the product of the connection probability between words is maximized is left and the hypothesis in which the product of the connection probability between words at the end of the sentence is maximized is selected.