Provided is a grass mowing machine capable of storing cut grass clippings in its grass collecting container in an efficient manner. The grass mowing machine includes a traveling machine body (10), a mower unit (6) supported to the traveling machine body (10), a grass collecting container (100) supported to the traveling machine body (10) and configured to store grass clippings cut by the mower unit (6), a conveyer duct (120) provided between the mower unit (6) and the grass collecting container (100) and configured to allow passage of the grass clippings therethrough, a guide member (130) for guiding the grass clippings, the guide member being provided inside the grass collecting container (100) at a position opposed to a charging inlet (102) of the grass collecting container (100) corresponding to a grass collecting container side end of the conveyer duct (120), and a posture changing mechanism (131) for changing posture of the guide member (130).
