Disclosed is a mobile terminal apparatus which includes: an upper housing in which a display portion having a display screen is disposed; a lower housing having an inner major surface in which an operating portion including a plurality of kinds of input keys is disposed; and a connecting portion which connects the upper housing with the lower housing such that the upper housing and the lower housing are turnable away from and toward each other to open and close the apparatus. In this apparatus, the inner major surface of the lower housing is recessed at an area where input keys of a first group that corresponds to a particular one of the kinds is disposed, so as to increase a level difference between a keytop of each of the input keys of the first group and the inner major surface.