A rocker arm (1), wherein guide faces (21) provided on both sides of an engagement surface (6) are tilted in such a direction that the guides faces near each other toward the tip thereof and, even if a valve element (20) is displaced in the lateral direction of the engagement surface (6), the base end part outer peripheral surface of the valve element (6) is allowed to abut only on the tip edge of either of the guide faces (21), whereby the performance of an engine can be easily increased by suppressing a frictional resistance acting between the guide face (21) and the base end part outer peripheral surface of the valve element (20) by increasing the lubricity of a contact part and reducing a frictional moment.
