To prevent a printing area on paper sheets by a second printing tool from fluctuating, in a printer configured such that paper sheets after printed by a first printing tool are once stored in a storing section and then transported to the second printing tool by a paper re-feeding device.

The printer includes: a first printing tool 3 for printing on one side of paper sheets P; a paper storing section 4 for temporarily storing the printed paper sheets P; a second printing tool 5 for printing on one side or the other side of the paper sheets P; and a paper re-feeding device 8B for transporting the paper sheets P printed on one side from the paper storing sections 4 to the second printing tool 5. In this printer, a relative position in the transporting direction of the paper sheets P for the plate surface 51a of the second printing tool 5 is adjusted by a printing position adjuster 83. Then, the relative position is adjusted corresponding to whether the printing process performed by the second printing tool 5 is a parallel printing process performed with the first printing tool 3 or a single printing process.