In this offset printing apparatus, a plate table (4) and a substrate table (6) are provided in a manner capable of traveling on guide rails (2) that are provided on a trestle (1). A transfer mechanism portion (9) that is provided with a blanket roll (10), lift actuators (13) of the blanket roll, a height sensor (14) of the blanket roll, and a pressure sensor (15) that detects the contact pressure of the blanket roll with respect to the plate (3) and the substrate (5) is provided at a position corresponding to the middle portion in the longitudinal direction of the guide rails (2). Also, a controller controls the lift actuators (13) so that the contact pressure that is detected by the pressure sensor (15) when the blanket roll (10) is brought into contact with the plate (3) and the substrate (5) becomes a predetermined value. Making uniform the contact pressure when performing transfer from the plate (3) to the blanket roll (10), and the contact pressure when performing retransfer from the blanket roll (10) to the substrate (5), makes the deformation amount of the contact portion with the plate (3) and the substrate (5) uniform, and equalizes the circumferential speed. As a result, it is possible to improve the printing accuracy.