A pen-shaped folding mouse (100, 200, 300, 400), comprising: a scroll wheel (110, 210, 310, 410, 510, 610), having an axis line; two supporting shafts (120, 220, 320, 420, 520, 620), disposed at two opposite sides of the scroll wheel (110, 210, 310, 410, 510, 610) and parallel to the axis line; two rod bodies (130, 230, 330, 430, 630), located at the two opposite sides of the scroll wheel (110, 210, 310, 410, 510, 610) and movably disposed on the two supporting shafts (120, 220, 320, 420, 520, 620), the two rod bodies (130, 230, 330, 430, 630) comprising two outer surfaces and two first end surfaces adjacent to the scroll wheel (110, 210, 310, 410, 510, 610); two buttons, disposed on the two outer surfaces of the two rod bodies (130, 230, 330, 430, 630); and an optical sensor, located on the outer surface of one of the rod bodies (130, 230, 330, 430, 630), wherein the two first end surfaces face the two opposite sides of the scroll wheel (110, 210, 310, 410, 510, 610) when the two rod bodies (130, 230, 330, 430, 630) are at a first position, the two rod bodies (130, 230, 330, 430, 630) and the scroll wheel (110, 210, 310, 410, 510, 610) extend along the axis line so that a pen shaft shape is presented, the two rod bodies (130, 230, 330, 430, 630) are adapted to move relative to the scroll wheel (110, 210, 310, 410, 510, 610) from the first position to a second position so that the two outer surfaces of the two rod bodies (130, 230, 330, 430, 630) face the two opposite sides of the scroll wheel (110, 210, 310, 410, 510, 610) and approach each other, the two rod bodies (130, 230, 330, 430, 630), the scroll wheel (110, 210, 310, 410, 510, 610), the optical sensor, and the two buttons form a mouse together, and the two buttons function as a left button and a right button of the mouse. a scroll wheel (110, 210, 310, 410, 510, 610), having an axis line; two supporting shafts (120, 220, 320, 420, 520, 620), disposed at two opposite sides of the scroll wheel (110, 210, 310, 410, 510, 610) and parallel to the axis line; two rod bodies (130, 230, 330, 430, 630), located at the two opposite sides of the scroll wheel (110, 210, 310, 410, 510, 610) and movably disposed on the two supporting shafts (120, 220, 320, 420, 520, 620), the two rod bodies (130, 230, 330, 430, 630) comprising two outer surfaces and two first end surfaces adjacent to the scroll wheel (110, 210, 310, 410, 510, 610); two buttons, disposed on the two outer surfaces of the two rod bodies (130, 230, 330, 430, 630); and an optical sensor, located on the outer surface of one of the rod bodies (130, 230, 330, 430, 630), wherein the two first end surfaces face the two opposite sides of the scroll wheel (110, 210, 310, 410, 510, 610) when the two rod bodies (130, 230, 330, 430, 630) are at a first position, the two rod bodies (130, 230, 330, 430, 630) and the scroll wheel (110, 210, 310, 410, 510, 610) extend along the axis line so that a pen shaft shape is presented, the two rod bodies (130, 230, 330, 430, 630) are adapted to move relative to the scroll wheel (110, 210, 310, 410, 510, 610) from the first position to a second position so that the two outer surfaces of the two rod bodies (130, 230, 330, 430, 630) face the two opposite sides of the scroll wheel (110, 210, 310, 410, 510, 610) and approach each other, the two rod bodies (130, 230, 330, 430, 630), the scroll wheel (110, 210, 310, 410, 510, 610), the optical sensor, and the two buttons form a mouse together, and the two buttons function as a left button and a right button of the mouse.