1. A speech recognition device, comprising: a microphone that converts an input speech into an electric signal; a speech recognizer to perform speech recognition for said electric signal with a speech recognition engine corresponding to a predetermined language that is a language that is set in advance as a recognition subject by referring to recognition subject word information including writing information and reading information of each recognition subject word included in a recognition subject vocabulary registered in a speech recognition dictionary; a first memory to store a reading information generation data base in which a reading information generation rule that indicates a correspondence between writing information of a word in one language among a plurality of languages and reading information thereof in another language is registered; a reading information generator to generate the reading information of the word in the another language from the writing information in the one language based on the reading information generation rule of the reading information generation data base; and a controller to perform control such that, when a word in a different language that is different from the predetermined language is included in the recognition subject vocabulary, the reading information generator generates the reading information in the predetermined language from the writing information in the different language, and that the speech recognizer performs speech recognition that makes reference to the recognition subject word information of the corresponding word, including the generated reading information in the predetermined language.