When, from a standby screen of a terminal device, a user depresses a motion key (S11) and performs a registered movement (S13), a sensor unit observes the movement of the terminal device, and a movement parameter calculation unit calculates a movement parameter. A movement parameter change decision unit decides (S15 and S16) whether or not a change of the movement parameter which is calculated, and a change of the movement parameter corresponding to a predetermined function registered in advance, agrees with one another. If the result of this decision is affirmative, a function control unit starts the corresponding function (S17). As a result, it is possible to set the terminal device to a state in which the predetermined function can be employed, with a simple and easily remembered actuation.