There are provided a piston rod having one end portion attached to a marine vessel propulsion machine main body; an inner cylinder; an inner piston mounted in the other end portion of the piston rod, dividing a space in the inner cylinder into a fourth chamber and a fifth chamber; an outer cylinder accommodating the inner cylinder therein; a cap covering an opening portion of one end portion of the outer cylinder; and an outer piston dividing a space in the outer cylinder into a second chamber and a first chamber, is formed with a through hole that allows the fourth chamber and the second chamber to communicate with each other, comes into contact with the cap to divide the third space into an inner space on a more inner side than the through hole and an outer space on a more outer side than the inner space.