To provide a personal digital assistant for performing a pen operation which is made available even when it is mounted on another case body such as an underwater housing.

The digitizer of a personal digital assistant is configured as an electromagnetic induction system, and provided with a switch or an electrode to recognize that the terminal is mounted on a housing so that the mounting of the terminal on the housing can be electrically recognized. When it is recognized that the terminal is mounted on the housing, the driving voltage of a stylus(pen) is increased so that stable recognizing precision can be maintained regardless of whether or not the terminal is mounted on the housing.