A sheet expanding apparatus includes: an adhering mechanism including an adhering roller by which a belt-shaped sheet wound in a roll form is adhered to a plate-shaped body, and a cutter adapted to cut the belt-shaped sheet into a rectangular sheet larger in size than the plate-shaped body; an expanding mechanism adapted to expand the rectangular sheet in a first direction and a second direction; and a transfer unit by which the plate-shaped body having the rectangular sheet adhered thereto is transferred to the expanding mechanism. The belt-shaped sheet can be supplied to the sheet expanding apparatus in the state of being wound in the roll form, and the plate-shaped body can be transferred by the transfer unit and the rectangular sheet can be expanded, after the belt-shaped sheet is adhered to the plate-shaped body and is cut into the rectangular sheet in the sheet expanding apparatus.