An image carrier unit includes: an image carrier having a circular cross-section and extending in one direction; an exposure device that radiates exposure light to the image carrier, the exposure device extending in the one direction and being opposed to the image carrier in a radial direction of the image carrier; a projecting member that is provided at both-end portions of the exposure device in the one direction, and projects to the image carrier along the radial direction; a formation member including an opposed surface that is opposed to a peripheral surface of the projecting member in a circumferential direction of the image carrier; a pressing member that presses the projecting member in the circumferential direction to press the peripheral surface of the projecting member against the opposed surface; and an adjusting member that adjusts a position of the exposure device relative to the image carrier by moving the exposure device in the radial direction with the projecting member pressed by the pressing member.