To provide a shaft coupling device which can endure an excessive axial strength.

In this joint system 10, an accumulated power condition is created by a compressive strain with an energized cushion 30 in a parallel direction with the center line between an inner material 20 and an outer material 11 which are arranged concentrically with each other and one end of the cushion material 30 is supported by a stopper ring 40 fitted into an annular groove which is formed in the inner periphery of a hollow part 12 of the outer material 11. In this case, the cross sectional shape of the fitting part of the annular groove 14 and the stopper ring 40 is formed into a wedge shape. In this way the force applied to the axial direction of the stopper ring bottom is divided into a component of force to push a slant face rectangular and a component of force parallel with the slant face on the slant face of the annular groove and the stopper ring, therefor, the phenomenon of the deficiency of the edge part of the annular groove or development of a crack in the groove bottom can be prevented.