A projector includes an anamorphic prism optical system for converting an aspect ratio of an irradiation region on which the video light is irradiated. The anamorphic prism optical system includes a first prism set and a second prism set. The first prism set is obtained by combining a first prism and a second prism, and the second prism set is obtained by combining a third prism and a fourth prism. The first prism, the second prism, the third prism, and the fourth prism are respectively rotatable around rotation axes thereof, and a space between the first and second prism sets is adjustable in association with the rotation of the first prism, the second prism, the third prism, and the fourth prism.