A blade attachment-detachment assisting apparatus includes a nut rotating part having an engagement pin that engages with an engagement hole of a nut, a nut grip part that grips an annular groove of the nut, a housing that supports the nut rotating part rotatably by a predetermined angle, and a lock mechanism. The nut rotating part is capable of advancing and retreating, relative to the housing, to a protrusion position and a fixing position at which engagement between the nut grip part and the nut is kept, and is fixed to the housing with the intermediary of a spring. The lock mechanism includes an inside surface by which advancing and retreating of the nut rotating part are restricted through engagement of the nut rotating part with the housing when the housing is rotated in one direction at the fixing position to which the nut rotating part has been pushed.