1. A projector that projects an image on a projection object, the projector comprising: an imaging structure that photographs the image projected on the projection object to take a photographed image; an imaging control module that performs average luminosity adjustment in the imaging structure to attain a preset target average luminosity; a control module that sets the target average luminosity in the imaging control module; an acceleration sensor that obtains angle information representing an inclination of the projector to the projection object; a storage unit that stores a map representing a variation in target average luminosity against the angle information, wherein the map sets a greater target average luminosity corresponding to a piece of the angle information representing a greater inclination; an analyzer module that analyzes the photographed image taken by the imaging structure and obtains positional information representing a peak position or a maximum brightness position in the photographed image; and an image processing module that adjusts the projected image, based on the positional information obtained by the analyzer module, wherein the control module controls the acceleration sensor to obtain the angle information, refers to the map stored in the storage unit to specify the target average luminosity corresponding to the obtained angle information, and sets the specified target average luminosity in the imaging control module.