A lawn mower (10) includes a driving source mounting portion (12) formed in a traveling frame (11), a driving source (13) mounted in the driving source mounting portion, and a lawn mowing unit (14) attached to the driving source. The lawn mowing unit is positioned below the traveling frame. A lower end (12b) of the driving source mounting portion and a lower end of the driving source are exposed from a bottom surface (17a) of the traveling frame. This bottom surface includes a frame-side seal surface (51) surrounding the lower end of the driving source mounting portion, and a lawn mowing unit peripheral surface (56) surrounding the frame-side seal surface. A waterproof member (70) is in tight contact with the frame-side seal surface, and waterproofs a portion between the bottom surface and driving source. When the lawn mower is viewed from below, the lawn mowing unit peripheral surface is formed over a range (Ar) from an outer circumferential edge (51b) of the frame-side seal surface to an outer circumferenti
