The image projection system includes a projection-type display apparatus that projects an image onto a projection plane and has a first azimuth detector, the first azimuth detector detecting a projection azimuth; an imaging apparatus that images a projection screen of the image and has a second azimuth detector, the second azimuth detector detecting an imaging azimuth; and a signal processor that performs correction processing of the image. The signal processor includes an estimation unit and a correction unit, the estimation unit estimating an inclination of the projection-type display apparatus to the projection plane on the basis of the projection azimuth detected by the first azimuth detector, the imaging azimuth detected by the second azimuth detector, and the captured image acquired by the imaging apparatus; and the correction unit correcting a shape of the projection screen on the basis of the inclination of the projection-type display apparatus estimated by the estimation unit.