Lawn mower

A lawn mower comprising:

• a power supply;
• a chassis for holding the power supply;
• a fixed shaft attached to the chassis;
• a rotary blade which is rotatably supported with respect to the fixed shaft;
• a transmitting portion which transmits rotation of the power supply to the rotary blade;
• a fixed blade which is coaxially-arranged with the rotary blade;
• an elastic member which presses the rotary blade toward the fixed blade;
• and
• a positioning portion which is configured to:
• vary a position of the rotary blade relative to the fixed blade in an axial direction of the fixed shaft, and
• regulate movement of the rotary blade toward a biasing direction of the elastic member at a plurality of positions, wherein:
• a distance between the rotary blade and the fixed blade can be varied by operating the positioning portion,
• the positioning portion is configured to set the position of the rotary blade in at least a first position and a second position,
• in the first position, the rotary blade strongly contacts with the fixed blade, and
• in the second position, the rotary blade weakly contacts with the fixed blade or does not contact with the fixed blade,
• the fixed shaft is a hollow member through which a rod penetrates, and a part of the rod is connected to the positioning portion,
• the position of the rotary blade in the axial direction of the fixed shaft is determined by the rod, and
• a position of the rod in an axial direction thereof is determined by the positioning portion.