To improve the efficiency of a chipper by cutting with a knife so that its edge line and the cutting direction cross at a slant to improve cutting performance and reduce cutting resistance.

The chipper mounted on a chipper work vehicle has a rotor. A disk-shaped knife disk 32 and a fan disk 34 are fitted to the rotary shaft 30 of the rotor. Cutting openings 320 are formed in two opposite places with the center of the diameter line of the knife disk 32 put between them, and the knives 33 are fixed to the fringe parts of the cutting openings 320. The angle of the edge line 331 of the knife 33 is set up to be parallel to the diameter line of the knife disk 32 at a necessary distance. A vertical receiving blade 24 is fixed to the front side of one fringe part in the vertical direction of an inlet 23, and a horizontal receiving blade 25 is fixed horizontally to the downward fringe in the cross direction of the inlet 23.