A projection device includes multiple optical fiber mounting mechanisms. Each of the optical fiber mounting mechanisms includes an optical fiber extending along a first direction as an axis direction, a signal circuit extending along the first direction, and a mounting structure. The optical fiber includes an engaging section. The mounting structure surrounds the engaging section of the optical fiber and the signal circuit. The mounting structure includes an installation portion extending radially relative to the first direction. The installation portion includes a surface and multiple elements exposed from the surface. The surface includes a normal direction parallel with the first direction. A first length of the engaging section of the optical fiber protruding from the surface of the installation portion is longer than lengths of the elements protruding from the surface.