A riding lawn mower includes: a delivery passage for delivering cut grass from a housing to a receptacle and a shutter mechanism provided on a lower portion of the delivery passage for switching the mower between a bagging mode in which cut grass is delivered from the housing to the receptacle and a mulching mode in which cut grass is discharged downward of the housing. The shutter mechanism includes a horizontal pivot shaft disposed on the lower portion of the delivery passage, and a shutter plate pivotable about the pivot shaft between a fully closed position where the shutter plate closes the delivery passage to place the mower in the mulching mode and a fully opened position where the shutter plate is laid down toward a discharge side of the delivery passage to place the mower in the bagging mode.
