PROBLEM TO BE SOLVED: To improve noise suppression performance by suppressing vortex flow of air occurring in a housing and to ensure lawn mowing performance.SOLUTION: A lawn mower 10 includes a cutter blade 14 stored in a housing 11 opened downward. The cutter blade is an elongated member extended in both directions horizontally with respect to a rotary shaft 15a extended vertically in the housing. Both ends of the cutter blade in the longitudinal direction are provided with air lift parts 44, 44 extended while curved from a front end in a rotation direction Ra to a rear and upper side. In a position 11f facing a rotary locus 46 of the air lift parts in an inner circumference surface 11e of a peripheral wall part 11b of the housing, plural wing parts 50 are formed in the whole circumference. The plural wing parts are projections projected inward from the inner circumference surface of the peripheral wall part and elongated vertically, or recesses recessed from the inner circumference surface and elongated vertically, the plural wing parts inclined to a side Re opposite to a curve direction Rd of the air lift parts.
