A mulching mower unit includes a mower deck, a rotary shaft, a blade, a shroud, and a deflector plate. The shroud has a circumferential wall including a rotational trajectory of the blade, and extends downward from a bottom surface of the mower deck to an area adjacent to the blade. The deflector plate is provided above the blade and radially outward of the rotary shaft in a running direction in an inner space of the shroud. The deflector plate includes a main body having an inner edge facing the rotary shaft and an outer edge spaced apart from the inner edge radially outward of the rotary shaft. The outer edge is positioned closer to the ground than the inner edge.