To provide a tail wheel for a plant husbandry machine ordinarily attachable to the machine body and selectively usable, according to the working state of the machine without separately preparing a single-wheel type tail wheel apparatus and a double-wheel type tail wheel apparatus.

The tail wheel 40 is attached to the front or back of a traveling wheel 15 of a plant husbandry machine 1. The tail wheel 40 is provided with a tail wheel support member 32 for attaching the wheel to the body of the husbandry machine or an implement; a pair of right and left wheels 34, 34 attached to the tail wheel supporting member 32; and a wheel support shaft 33 to rotatably support the wheels 34, 34 on the tail wheel support member 32. A tail wheel arm 35, having a portal form by back view, is placed under the tail wheel support member 32, the wheel supporting shaft 33 is laterally extended between the right and left vertical arms 35b, 35b of the tail wheel arm 35, in a detachable manner; the wheels 34, 34 have a wheel part 34a and a boss part 34b protruding from the side face of the center of the wheel part 34a; and the right and left wheels 34, 34 are detachably and rotatably supported on the wheel supporting shaft 33.