To provide a portable terminal device which can easily perform operation for switching the kind of characters to be inputted without reducing the speed of character input, and permits such operation with one hand.

The portable terminal device 30 for outputting a character on a display unit 4 in correspondence with the input operation of character by an operation part 8 has a plurality of input modes for changing the kind of characters to be inputted. The device has a tilt angle detecting element 46 for detecting the tilt angle of own device; a storage 44 for storing the tilt angle; and a control unit 48 which, during the input operation of character by the operator after storing the tilt angle detected by the tilt angle detecting element as a reference tilt angle in the storage, controls so as to switch the input mode if the tilt angle detected by the tilt angle detecting element changes, a relative angle between the tilt angle and the reference tilt angle stored in the storage becomes larger than a predetermined angle, and then the tilt angle returns to the reference tilt angle.