PROBLEM TO BE SOLVED: To provide a waste straw cutting apparatus facilitating long size or short size changeover operation of waste straw cutting length and forming a changeover mechanism of the waste straw cutting length as a simple structure.SOLUTION: In a waste straw cutting apparatus 20 equipped with a first rotational shaft 22 in which a plurality of first large-diameter rotary blades 22a and a plurality of first small-diameter rotary blades 22b are alternately fixed and a secondary rotary shaft 23, in which a plurality of secondary rotary blades 23a are fixed and arranged adjacently to or separably from the first rotary shaft 22 and a changeover mechanism 30 enabling changeover and fixation of the second rotary shaft 23 to an adjacent position P2 or a separate position P1, and capable of changing over cutting length of waste straw to long length or short length, the changeover mechanism 30 comprises a cam 32 enabling changeover and fixation of the second rotary shaft 23 by locking it on a first positioning member 31a or a second positioning member 31b by swinging.COPYRIGHT: (C)2009,JPO&INPIT【課題】排藁切断長の長短切替操作を容易にし、排藁切断長の切替機構を簡易な構造とする排藁切断装置の提供を目的とする。【解決手段】複数の第一大径回転刃22aと複数の第一小径回転刃22bを交互に固定した第一回転軸22と、複数の第二回転刃23aを固定するとともに、第一回転軸22に対して近接または離間可能に配置した第二回転軸23と、第二回転軸23を近接位置P2または離間位置P1に切替固定可能とする切替機構30とを備え、排藁の切断長を長短切替可能とする排藁切断装置20において、切替機構30は、揺動させることで第一位置決め部材31aまたは第二位置決め部材31bに係止して第二回転軸23を切替固定可能とするカム32を具備する。【選択図】図4