A light guiding object for use in a lighting device is provided. The light guiding object includes a cylindrical body, a reflective layer, a transparent resin layer and a light-adjustable film. The cylindrical body has a light-entering surface and a bottom surface. The reflective layer is disposed on the bottom surface of the cylindrical body. The transparent resin layer is disposed on the light-entering surface of the cylindrical body. The light-adjustable film has a flat surface and an optical structure surface, wherein the flat surface is opposite to the optical structure surface and disposed on the transparent resin layer. A central part of the optical structure surface includes a first prism group. The first prism group includes a plurality of first prisms, wherein the apex angles of the first prisms are in a range of 120 to 170 degrees.