This
breather apparatus has a rotation separator that is fastened to a
camshaft, and that rotation separator has a base plate section and a plurality of protruding plates that extend from the base plate section. Moreover, a separator housing is provided in the
cylinder head, and comprises an air intake on one end, and an exhaust outlet on the other end. Furthermore, a
reed valve that opens and closes by the change in pressure inside a
cam chamber is provided in the air intake. Blowby gas that is guided to the
cam chamber hits against the protruding plates when passing in the radial direction of the rotation separator, and
oil mist is captured by those protruding plates. Continuing, the blowby gas is guided from the
cam chamber into the separator housing via the
reed valve. When passing through the
reed valve, the flow rate of the blowby gas changes, so
oil mist is effectively captured by the inner wall surface of the separator housing.