When a navigation device receives an input of speech from a user, it transmits data of inputted speech to a server and receives a speech recognition result. If a guide route includes a communication impossible area, the navigation device obtains terminal-use speech recognition data necessary for the navigation device to perform speech recognition from the server before reaching the communication impossible area. Thus, even if the speech is inputted by the user while traveling the communication impossible area, the navigation device can perform the speech recognition by itself by using the terminal-use speech recognition data.