A lens adjusting mechanism including a base, a first fastening component, a first bracket, a second fastening component, a second bracket, and a lens is provided. The first fastening component is movably connected to the base along a first straight direction. The first bracket is movably connected to the base along the first straight direction through the first fastening component. The second fastening component is connected to the first bracket. The second bracket is movably connected to the first bracket along a second straight direction through the second fastening component, wherein the first straight direction is different from the second straight direction. The lens is disposed on the second bracket.