A lawn mower includes: a rotation shaft extending vertically in a downwardly-opening housing; and a cutter blade rotatably mounted on the rotation shaft. The cutter blade is an elongated member extending in opposite horizontal directions and having two bent sections formed on respective ones of its longitudinally opposite end portions. The two bent sections are bent in opposite directions as viewed in the axial direction of the rotation shaft. The cutter blade has, on each of the bent sections, a convex cutter blade section formed along a convex edge of the bent section and a concave cutter blade section formed along a concave edge of the bent section. The convex cutter blade section on each of the bent sections has a smaller cutting edge angle than the concave cutter blade section.