A lawn mower includes a housing with an opened bottom, a hollow shaft extending in a vertical direction of the housing and including a lower end positioned within the housing, a cutter blade, flaps provided for at least part of the cutter blade in a manner that the flaps have a flap angle changeable along a horizontal line, an actuator for outputting an output to control the flap angle of the flap, and a transmission mechanism accommodated in the hollow shaft for transmitting the output of the actuator to the flaps.
