A hinge device capable of reducing a reduced-size biaxial structure that can selectively switch rotations of two shafts according to an opening/closing angle position between two chassis is disclosed. The hinge device includes a first shaft attached to a first chassis, and a second shaft attached to a second chassis. The first shaft includes a recess located on an outer peripheral surface of the first shaft, and the second shaft includes a recess located on an outer peripheral surface of the second shaft. The hinge device also includes a lock member having a first projection engageable the said first recess, a second projection engageable with the second recess, and an arm member coupling the first projection to the second projection. The lock member allows rotation of one of the first shaft or the second shaft and restricts rotation of each other according to an opening/closing angle position between the first chassis and the second chassis by alternately performing engagement of the first projection with said first recess and engagement of the second projection with the second recess by means of sway of the arm member.