A projection apparatus including a digital micro mirror device (DMD), a light source, a lens, a photoelectric conversion device, a decision device and an adjustment module is provided. When the DMD is switched to a first operating state, the DMD reflects a light beam emitted by the light source to the lens. When the DMD is switched to a second operating state, the DMD reflects the light beam to the photoelectric conversion device. The photoelectric conversion device generates a signal value according to a light intensity of the light beam. The decision device compares the signal value with a predetermined value. When the signal value is smaller than the predetermined value, the decision device generates a driving signal value. The driving signal value is used for driving the adjustment module to sequentially adjust a position of the light source along a plurality of axes.