An image projection and detection apparatus including an illumination system, a digital micro-mirror device (DMD), an optical detector, and a total internal reflection (TIR) unit is provided. The illumination system provides an illumination beam. The DMD is disposed in an optical path of the illumination beam, and includes a plurality of micro-mirror structures switched between an on-state and an off-state. When at least a part of the micro-mirror structures are in the on-state, they reflect the illumination beam into an image beam transmitted to an object side. When at least a part of micro-mirror structures are in the off-state, they reflect an object beam from the object side to the optical detector. The TIR unit includes a first TIR surface and a second TIR surface. The first TIR surface totally reflects the illumination beam to the DMD. The second TIR surface totally reflects the object beam to the optical detector.