A clippings collecting-discharging device includes: a bucket on a lawn mowing unit divided into a main body part including a clippings flow inlet and a movable part connected to an upper end of the main body part, and can be operated between a closed position where the main body part and the movable part abut against each other and an open position where the movable part is rotated upward and separated from the main body part; a discharge plate in the bucket positioned near the inlet in a lying posture when the bucket is closed; and a discharge mechanism where the discharge plate stands up toward an opening between the main body part and the movable part while interlocking with the operation of the bucket, which position is changed to the open position.