Patent ID: 8532711

Claim:
A mobile terminal device provided with a plurality of keys and a certain key located at a side surface which is different from a surface where the plurality of keys are located in a phone chassis, the mobile terminal device comprising: a touch detector configured to detect touching any of the keys and the certain key by a user; a press detector configured to detect pressing any of the keys and the certain key by the user; a mode switcher configured to switch a mode of a group of the keys to a first mode in which at least a first function selected from a group comprising calling a mail editing screen and calling a screen for using the Internet is available in a case where the user touches the certain key, which is not one of the group of the keys, and to switch the mode of the group of the keys to a second mode in which at least a second function selected from a group comprising calling a menu screen and calling a jump screen is available in a case where the user does not touch the certain key; a function executor configured to execute the first function assigned to an input key, which is a key different from the certain key and is one of the group of the keys, in a case where the press detector detects in the first mode that the user has pressed the input key among the plurality of keys, and to execute the second function assigned to the input key in a case where the press detector detects in the second mode that the user has pressed the input key; and an output unit including a display screen configured to display a plurality of explanations of the first function assigned to each key of the group of the keys in a case where the touch detector detects that the user has touched the certain key and the explanation of the first function assigned to a specific one of the keys is not associated with the specific one of the keys on the display screen until the specific one of the keys is pressed, wherein the output unit outputs an explanation of the second function assigned to the input key in a case where the touch detector detects in the second mode that the user has touched the input key, and wherein even if a detected status has been changed from touching the certain key by the user to not touching the certain key, the mode switcher keeps the first mode until a timer reaches a predetermined time without switching the mode from the first mode to the second mode.