To eliminate positional deviation when the positional deviation of writing in right and left directions occurs in images formed on both sides of a recording medium.

An image forming apparatus includes: resist rollers for correcting oblique traveling of the recording medium; an image forming section for forming the image; the double-sided unit 7 constituting at least a horizontal path portion in a reverse path, and configured to make the recording medium, with the image formed by the image forming section, travel along the reverse path, and thereby making the recording medium upside down to return the recording medium to the resist rollers; conveying rollers on the reverse path to make the recording medium travel along the reverse path; an attachment part 32 provided inside a housing 31 so as to freely attachably/detachably support the double-sided unit; and an adjusting section 35 to adjust the right and left inclination of the double-sided unit with respect to the traveling direction of the recording medium on the reverse path when the double-sided unit is installed inside the housing through the attachment part.