A lawn mower has a scroll portion for allowing grass clippings to swirl within a housing while guiding them to a grass discharge passage. A guide provided beneath a top plate of the housing is placed along the scroll portion. A rear guide end of the guide is opposed to a passage opening facing the housing of the grass discharge passage. The direction of a swirling flow is gradually changed and guided toward the passage opening by the guide. A pivotal shutter pivotal about a generally vertical axis is provided for opening and closing the grass discharge passage.
