To perform work for axially moving the attaching shaft 32, which supports free hammer-like crushing blades 33, of a crushing mechanism 3 in an unrestricted state without requiring complicated operation at the time of inspection work of the crushing mechanism 3 in such a state that a crushing chamber 2 is opened upward by opening a cover (b).

This agricultural chopper is constituted by forming the region 10a becoming the ceiling part of the crushing chamber 2 to the cover (b) which is opened, closed and revolved with respect to a machine frame 1 by a hinge 11. The region (c), which reaches the cover (b) of the upper surface of the machine frame 1 from the outside of the bearing mechanism part (d) of a main shaft 30, including the region superposed on the revolving locus (w) of the attaching shaft 32 of the crushing blades 33 of the crushing mechanism 3 on a side view of the side wall 12 of the machine frame 1 is cut off as a separate body from the side wall 12 of the machine frame 1 and the upper edge side of the region (c) is connected to and supported on the side edge part of the cover (b).