PURPOSE: To facilitate adjusting operation by connecting a spring retainer for holding a valve to a valve lifter by screws so that the amount of clearance between the valve and the spring retainer may be adjusted, and providing through holes and screw holes through a plane intersecting the direction of valve movement at right angles in order to screw fixing screws into these holes.

CONSTITUTION: A valve 3 is fixed to a spring retainer 7 and then mounted to a valve lifter 4 using screw pairs. The valve 3 is inserted into the valve holding hole of the spring retainer 7, the male screw on the outer peripheral surface of the spring retainer 7 is screwed in the female screw on the inner peripheral surface of the valve lifter 4, and the valve 3 is then turned to adjust valve clearance. Plural holes are provided circumferentially on the top face of the valve lifter 4, plural screw holes are provided circumferentially in the spring retainer 7, and the valve lifter is fixed to the spring retainer by fixing screws 12. Since the valve 3 can be turned so as to be fixed at the posirion where a moderate valve clearance has been reached. Thus, the adjusting operation can be performed simply and in a short time.