An optical scanning imaging/projection apparatus includes a light source that outputs illumination light and projection light in the visible range, an optical scanner that scans the illumination light and the projection light, which are output from the light source, along a predetermined scanning trajectory, a switch that switches the output from the light source so that the illumination light and the projection light are alternately output, an optical detector that detects observation light generated by a subject irradiated with the illumination light, a storage that stores data in which an intensity of the detected observation light detected is associated with information indicating a detection position on the scanning trajectory, and a projection light controller that controls, on the basis of the data stored in the storage unit, an intensity of the projection light to be applied to each position on the scanning trajectory.
