To provide a gripper unit for giving a suitable tension to several types of printing plates having different tensile strengths.

A plurality of spring containing holes 46 are formed at a clamping base 31 of a trailing side clamping unit 30 for holding a winding end side of a printing plate A to be wound on an outer periphery of a plate cylinder 1, and the base 31 is pressed in a direction separating from a wall surface 3b of a clamp containing recess 2 by a spring 47 contained in a spring containing hole 46. A rod 48 having a flange 48a is inserted into springs 47 of half number of a plurality of springs 47. An end of the rod 48 is slidably passed to a closed end wall of the container 46, a nut 52 is engaged with male threads 48b formed on its end, an elastic force switching plate 54 is provided insertably or drawably between opposed surfaces of the nut 52 and the base 31, the plate 54 is inserted between the opposed surface of the nut 52 and the base 31, the spring 47 is held in a contracted state, thereby regulating the force for pressing the base 31 by the springs 47.