To provide a reversal cylinder structure in a machine for forming an IS type glass.

This reversal cylinder structure in a machine for producing an IS type glass container has a piston capable of moving along a straight line pathway between an inside position and an outside position of a ring-like housing 18. As a result, a cylinder rod 20 installed in the piston is extended from the ring-like housing 18, and drawn in the ring-like housing 18 again therefrom. A shock absorber 28 is arranged in the recess of the ring-like housing 18, and a longitudinal central shaft of the shock absorber 28 is arranged at a distance from the longitudinal central shaft of the rod 20 in parallel. When the piston arrives at the outside position, the shock absorber 28 engages with the piston so that the shock absorber 28 may absorb the inertia load when the piston reduces the speed toward the outside position. After the shock absorber 28 is turned around the longitudinal central shaft 12 of the rod 20, the shock absorber is taken out through an opening 24.