It is intended to suppress rattling in the fitted state of segments to improve operating efficiency in bonding the segments together. Error generation circuitry in a power converter may generate an error signal based on the difference between a power converter output voltage and a reference voltage. The user interface may then be expanded to also display user interfaces associated with the application that was selected, as well as the user interfaces associated with the e-mail program. The control module is in communication with each of the field sensors. On a back surface of the main body case 5, 50 or 51, a slip preventing part 13 that prevents the telephone from being dropped is provided. Acceleration is disabled when the internal state indicates a risk of instability.