An object is to provide a printing press that has a printing plate with a changeable diameter and that can sufficiently prevent oil and oil mist from entering a printing unit. A rotary press (1) having a blanket cylinder (17) with a changeable diameter is provided. The rotary press (1) includes a driven-side frame (23) provided on the circumference of a hole (49) formed in the driven-side frame (23), the driven-side frame (23) extending in a direction substantially orthogonal to the axial direction of a printing cylinder and protruding toward a shaft (33) of the printing cylinder, the shaft (33) passing through the hole (49) formed in the driven-side frame (23); and a first blanket-side labyrinth plate (83) provided around the shaft (33), the first blanket-side labyrinth plate (83) being provided substantially parallel to a first frame-side labyrinth plate (67) in the axial direction, with a gap formed between the first frame-side labyrinth plate (67) and the first blanket-side labyrinth plate (83), wherein an end position of the first frame-side labyrinth plate (67) and an end position of the first blanket-side labyrinth plate (83) are set so that the first frame-side labyrinth plate (67) and the first blanket-side labyrinth plate (83) overlap when the blanket cylinder (17) moves to any position in response to a change in the diameter.