There is described a cutting device (40) for a lawnmower (10) comprising: a cutting tool (41) having horizontal rotation axis, a guard (60) adapted to delimit an inner volume wherein there is accommodated the cutting tool (41), and a system (100) for collecting the cut grass, wherein said collection system (100) comprises: a casing (122) provided with at least one inlet opening (104, 125) and with one outlet opening (107) for the cut grass, and at least one conveyor member (121) placed inside the casing (122) and adapted to convey the cut grass from the inlet opening (104, 125) towards the outlet opening (107), wherein the guard (60) of the cutting tool (41) comprises at least one wall (142) that is movable between a first operating position wherein the inner volume of the guard (60) communicates with the inlet opening (104, 125) of the casing (122) of the collection system (120), and a second operating position, wherein the inner volume of the guard (60) is separated from the inlet opening (104, 125) of the casing (122) of the collection system (120).
