To provide a chopper simple in detachment in cleaning without requiring adjustment of the level of pressure contact between an extrusion plate and a rotary cutter.

In this chopper including a feed screw 2 laterally installed in a cylinder 1, and an extrusion plate 6 energized to always subject a rotary cutter 5 connected to a distal end part of the feed screw 2 to pressure contact, a male screw fastening with rotation of the feed screw 2 is formed in an outer periphery of the extrusion plate 6, and the extrusion plate 6 is mounted to the cylinder 1 by screwing the male screw to a female screw formed in an inner periphery on the exit side of the cylinder 1.