A lawn mower (10) includes a hollow shaft (41), a cutter blade (14), flaps (52), a belt type continuously variable transmission (32), and a transmission mechanism (70). The cutter blade (14) extends along a horizontal line (46) which is perpendicular to the hollow shaft (41). The flaps (52) are provided for the cutter blade (14). Each of the flaps (52) has a flap angle (¸r) changeable along the horizontal line (46). A control force converter unit (60) of the belt type continuously variable transmission (32) converts a displacement force of the movable sheave (37) relative to the fixed sheave (36) in an axial direction into a control force that controls the flap angle (¸r) of the flaps (52). The transmission mechanism (70) is accommodated inside the hollow shaft (41), and transmits the control force to the flaps (52).
