1. A lawn mower, comprising:a work unit including a housing having a downward-facing opening and a cutter blade rotatably provided in the housing such that when rotated, the cutter blade cuts grass and generates a transport air flow flowing from the opening of the housing to inside;
a grass clippings receptacle configured to receive mowed grass clippings;
a grass clippings transport passage connecting an interior of the housing with the grass clippings receptacle;
a shutter device including a shutter configured to open and close the grass clippings transport passage and an actuator configured to open/close-drive the shutter;
a controller configured to control the shutter device; and
a speed sensor for detecting a travel speed of the lawn mower,
wherein the controller is configured to open/close-control the shutter device based on the travel speed.