A mown-grass collecting bucket capable of smoothly collecting into a mown-grass collecting box the grass mown off by a lawn mower cutters and automatically discharging out of the box the mown grass collected into the box and scraped together is provided. The mown-grass collecting box having intake and discharge ports for the mown grass is provided with a mown-grass scraping-together and discharging mechanism, which mechanism comprising a rotary shaft coupled to a rotary drive source to be driven thereby, a first blade supported through first brackets by the rotary shaft, a second blade supported through second brackets mounted to support shafts provided on the first brackets, a brush provided to tip edge of the second blade, and twist springs each mounted on each support shaft and across each first bracket and each second bracket.