A rotor apparatus for a baler is provided such that hay on the ground is picked up by a hay pick-up apparatus installed at the side of the baler and the picked-up hay is fed without being wound around the rotor feeding the hay to the region of the roll forming apparatus, whereby the hay of the hay pick-up apparatus is fed to the region of the roll forming apparatus quickly, precisely, and evenly. In addition, a load of the rotor is minimized when the hay is fed to the region of the roll forming apparatus, thereby extending the service life of the rotor.