A mower unit is provided which includes: a blade unit (77) including a rotary shaft (79) haying a rotary axis (XI) extending in a vertical direction and a blade (78) which is provided on the rotary shaft (79) and rotatable about the rotary axis (X1)； a blade housing (7) that covers the blade unit (77) from above to create a mowing space (Z0) therein and is provided outside thereof with a recess (S1) spreading radially from the rotary shaft (79)； a deck lid (75) that covers the recess (S1) from above to create an intermediate space (S1)； a primary air flowing part (91) that allows air to flow between outside and the intermediate space (S1)； and a secondary air flowing part (92) that allows air to flow between the intermediate space (S1) and the mowing space (Z0).
