To operate one cylinder in multistages by putting the rod of one piston through the other piston in a vertical direction and protruding the rods of these pistons to outside from one end of the cylinder in a coaxial manner.

A two-stage cylinder 51 includes one cylinder 53, a partition wall 57 for dividing the inside of the cylinder 53 into two space parts 55a and 55b and first and second pistons 61a and 61b respectively provided in the two continuous space parts 55a and 55b partitioned by the partition wall 57. In this two-stage cylinder 51, the rod part 83a of the first piston 61a penetrates the partition wall 57, the piston part 81b and the rod part 83b of the second piston 61b. The two pistons 61a and 61b are separately driven.