An optical path folding element includes an optical portion, a connection portion, matte structures and a light blocking layer. The optical portion has an optical surface and two reflective surfaces. A light beam enters into the optical path folding element via the optical surface and is reflected inside the optical path folding element through the optical surface. Each reflective surface is configured to reflect the light beam again inside the optical path folding element. The connection portion has connection surfaces connected to the optical surface and the reflective surfaces. The matte structures are at least disposed on and integrally formed with the connection portion. Each unitary structure of the matte structures is tapered off and recessed from the connection portion, such that the outer surface of the connection portion has an undulating shape. The light blocking layer is at least disposed on the connection portion for blocking light.