A valve train of an internal combustion engine equipped with a valve reciprocated by a cam is equipped with a spring seat manufactured in order to prevent the surging of a coil spring. A spring seat having a squeeze film effect of damping the axial motion of a coil spring is provided at one end of the coil spring in a closing direction. The spring seat is configured to be provided with an oil slit which radially intersects and extends helically around a valve axis.