A lawn mower (10) includes a housing (11), a drive source (15), flaps (52), a grass clippings container (22), a grass clippings container weight detection unit (113), an internal pressure detection unit (111), and a control unit (117). If it is determined that a first condition where a change amount (ΔWr) per predetermined fixed time (Δt1) of the weight (Wr) detected by the grass clippings container weight detection unit (113) is below a weight change amount reference value (ΔWs) and a second condition where a change amount (ΔPr) per predetermined fixed time (Δt2) of the internal pressure (Pr) detected by the internal pressure detection unit (111) has increased to a internal pressure change amount reference value (ΔPs), are satisfied, the control unit (117) implements control to place the flaps (52) in a substantially horizontal state.
