A post-processing device includes: a passage that extends in one direction; a post-processing section that is movable on a plane along the passage and that is stopped at plural post-processing positions, including a stop position determined in advance, to perform post-processing on a recording medium; and a positioning portion which is provided at the stop position and against which an end portion of the recording medium abuts when the post-processing section performs the post-processing at a post-processing position other than the stop position, the positioning portion being retracted with respect to the post-processing section when the post-processing section passes through the stop position or is moved toward the stop position.