A projector includes a projecting module for projecting a projecting image on a screen panel, an image sensor for capturing an image of an object which is located outside of the projecting module and faces toward the lens module, a light director, and a controlling unit. The projecting module has a lens module and a light source for emitting light transmitting through the lens module. The light director is movable between a first position where the light director is located outside of a light path associated with the lens module, and a second position where the light director is configured for directing light of the object through the lens module to be incident on the image sensor. The controlling unit controls the light director to move between the first and second positions.