A rocker arm unit constituting a valve gear includes a support member, a rocker arm including a roller and walls opposed to each other with the roller being interposed between them and a wire member bridging the support member side and the rocker arm side with each other. The walls have shaft holes into which both ends of a shaft member rotatably supporting the roller extend respectively. The walls have lengthwise ends connected to each other via a receiving portion supported on a top of the support member so that the rocker arm is swung. The wire member has an extending portion extending from the support member side to the rocker arm side and having a distal end. The rocker arm side includes a part located away from the receiving portion. The distal end of the extending portion serves as an engagement portion engaging the rocker arm side part.