An image projection apparatus includes: an illuminance sensor for measuring surrounding illuminance; an image data processing unit that increases a gradation value of the image data in accordance with brightness of the image data; a set information storage unit for storing at least two or more pieces of correspondence information for each range of the obtained illuminance, the information indicating correspondence between the brightness of the image data and power a light source that increases in accordance with the brightness; a total control unit for determining the lamp power by referring to a table indicating the correspondence information, based on the obtained brightness of the image and the illuminance; and a projection unit for projecting with the determined lamp power the image data, wherein in the correspondence information, a value of the lamp power is set lower as the illuminance becomes lower.