The present invention relates to a valve train for an engine. The valve train for an engine according to an embodiment of the present invention comprises a valve opening and closing an inhalation port or an exhalation port; a cam shaft vertically reciprocating the valve; a return spring surrounding a part of the valve; and a rotational retainer combined with one side of the valve with the return spring, and delivering twist generated by the return spring repeating compression and expansion during a vertical reciprocating motion of the valve to rotate the valve in one direction.
