A lawn mower includes a housing, a drive source, flaps, a grass clippings container, a grass clippings container weight detection unit, an internal pressure detection unit, and a control unit. If it is determined that a first condition where a change amount per predetermined fixed time of the weight detected by the grass clippings container weight detection unit is below a weight change amount reference value and a second condition where a change amount per predetermined fixed time of the internal pressure detected by the internal pressure detection unit has increased to a internal pressure change amount reference value, are satisfied, the control unit implements control to place the flaps in a substantially horizontal state.