A portable information device is capable of stably supporting a foldable display. The portable information device has a support plate which is fixed to the inner surface sides of a first chassis member and a second chassis member and supports the rear surface of a display. The support plate has a first plate member disposed on the inner surface side of the first chassis member, a second plate member disposed on the inner surface side of the second chassis member, and a flexible sheet-like member connecting the first plate member and the second plate member so as to be foldable into a double-folded state.