The present invention provides a variable valve mechanism, which includes a rocker arm including an input member and an output member; a switching device that switches a drive state of the valve by displacing the switching pin between a coupling position at which the switching pin extends between the first pinhole in the input member and the second pin hole in the output member and a non-coupling position at which the switching pin does not extend; and a lost motion spring. A displacement clearance is formed between an inner peripheral surface of the first or second pin hole and an outer peripheral surface of the switching pin to permit the relative displacement in a range of the displacement clearance at a coupled time so that a tappet clearance is not formed with the input member urged toward the cam by the lost motion spring.