A mobile terminal device having a route guiding function of guiding a route by obtaining map information from a server system via a radio communication network includes: a position detecting unit which detects a current position of the mobile terminal device; a bearing detecting unit which detects a first bearing to which the mobile terminal device is directed; a target bearing calculating unit which calculates a second bearing from a current position to the destination; a displaying unit which displays a map based on the acquired map information on a section containing the destination and the current position, displays icon images at a position of the destination and the current position respectively, and displays an icon image indicating the first bearing; and a target capturing unit which produces a sound effect in response to a difference between the first and second bearings.