A rocker arm mechanism in an OHC type engine which includes a cam which is rotatable while interlocking with a crank shaft; and a rocker arm which oscillates in accordance with the rotation of the cam so as to open and close an intake valve and an exhaust valve, characterized in that the rocker arm includes a rocker arm body and a pad member rotatably fitted to the rocker arm body and adapted to be a contact portion to the cam, and that the cam and the pad member are brought into contact with each other such that the pad member may rotate due to a frictional force generated between the cam and the pad member as the cam rotates.