Disclosed is a mower with a mower deck, a plurality of cutting chambers mutually communicated and arranged in a lateral direction within the mower deck, and a blade mounted in each cutting chamber to be rotatable about a vertical axis. A grass clippings guide in form of a vertical wall is disposed in an upper area within the cutting chamber, to guide the grass clippings flowing within the cutting chamber toward a center of rotation of the blade. A shield member is disposed for preventing entry of grass clippings between the grass clippings guide and a peripheral wall of the cutting chamber.