A portable information device includes: a first chassis; a second chassis coupled to the first chassis to be rotatable relative to the first chassis; and a cover device having a first cover section which covers the back surface of the first chassis, a second cover section which covers the back surface of the second chassis, and a folding cover section which connects between the first cover section and the second cover section to be rotatable relative to each other. The cover device further has a sheet-shaped member provided to face a side edge of the folding cover section on the inner surface side of the folding cover section and provided to be movable relative to the inner surface of the folding cover section.