Patent ID: 7925312

Claim:
A mobile terminal device comprising: a lower casing; an upper casing; and an intermediate casing connected to the lower casing by a hinge structure which enables the intermediate casing to rotate about an axis, the intermediate casing supporting a back surface of the upper casing by a front surface of the intermediate casing, wherein a first casing which is either the upper casing or the intermediate casing has a first groove formed in a vertical direction with respect to the rotation axis on a surface facing a second casing which is the other of the upper casing and the intermediate casing, the second casing has a first portion protruding from a surface facing the first casing and fitting the first groove of the first casing, the first portion moving upward or downward under a guidance of the first groove, and the upper casing rotates with respect to the intermediate casing for the portion being guided by the first groove.