A riding lawn mower includes: a delivery passage (22) for delivering cut grass from a housing (20) to a receptacle (51) and a shutter mechanism (80) 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 (82) disposed on the lower portion of the delivery passage, and a shutter plate (83) pivotable about the pivot shaft between a fully closed position where the shutter plate closes the delivery passage to execute the mulching mode and a fully opened position where the shutter plate is laid down toward a discharge side of the delivery passage to execute the bagging mode.
