Image projection system and method for adjusting projection position

A displacement calculation unit (161) creates a command for correcting the displacement in each projection image and a size deviation calculation unit (163) creates a command for correcting the size deviation in each projection image on the basis of a captured image captured from each projection image projected on a screen using projectors (4, 5). The projectors (4, 5) move the position of each projection lens in accordance with these commands, and correct the position and size of each projection image. An error evaluation unit (154) creates a command for correcting the distortion of the projection image due to the distortion of the projection lens, and a projection angle distortion calculation unit (162) creates a command for correcting the distortion of the projection image due to the projection angle on the basis of the captured image captured after correction. The projectors (4, 5) transform each image displayed on each display element in accordance with these commands to correct the distortion of each projection image.