The present disclosure provides a double-sided printing paper conveying unit, including a paper conveyor configured to convey paper in a conveying direction, a guiding part configured to guide the paper conveyed by the paper conveyor, an aligner movably mounted on the guiding part, and configured to correct a skew posture of the paper during conveyance in an alignment direction perpendicular to the conveying direction; and a movement mechanism mounted on the guiding part and capable of moving the aligner along the alignment direction and between a first position corresponding to a first size of paper and a second position corresponding to a second size of paper such that the aligner aligns the paper based on a size of the paper. In addition, the present disclosure also provides an imaging apparatus that includes the double-sided printing paper conveying unit.