A lawn mower includes a driving source mounting portion formed in a traveling frame, a driving source mounted in the driving source mounting portion, and a lawn mowing unit attached to the driving source. A bottom surface of the traveling frame includes a frame-side seal surface surrounding the lower end of the driving source mounting portion, and a lawn mowing unit peripheral surface surrounding the frame-side seal surface. A waterproof member is in tight contact with the frame-side seal surface. The lawn mowing unit peripheral surface is formed over a range from an outer circumferential edge of the frame-side seal surface to an outer circumferential edge of the lawn mowing unit. A boundary between the frame-side seal surface and lawn mowing unit peripheral surface is formed into the shape of a step.
