A control unit obtains a current position of a mobile phone by using a GPS receiver during the operation of the navigation function, while detecting a style of a device body based on detection of an opening/closing sensor. The control unit determines whether to perform route guidance or to perform direction guidance based on the detected style of the mobile phone. When the mobile phone is in “open style”, the control unit displays a detailed navigation screen including route indicating map images on a main display, while displaying a simple direction guidance on a sub display when the mobile phone is in “closed style”.