According to one embodiment, a finite state transducer determinizing device includes a symbol determination unit, a state merging unit, and a single-value processing unit. The symbol determination unit generates an identification symbol different from an input symbol assigned to each transition of a finite state transducer. The state merging unit extracts one or more states at a transition destination by the same input symbol from among the states of the finite state transducer and generates states having the extracted states as sub-states. The single-value processing unit applies the input symbol assigned to each transition of the finite state transducer or the identification symbol as an input symbol of a transition between the states generated by the state merging unit to perform determinizing.