A seat includes a seat back for supporting a back of a seat occupant and a shoulder harness including at least one shoulder strap for restraining a shoulder of a seat occupant. The shoulder strap has a rear portion anchored in a manner enabling it to move in a height direction of a seat occupant. When the seat occupant tightens the shoulder strap, the rear portion can move in response to the tension to a position in which the shoulder strap extends substantially perpendicular to the back tangent line of the seat occupant. In this manner the shoulder strap can be automatically be adjusted in position for a wide range of seat occupants of varying heights.