To provide a brake capable of enhancing a degree of freedom of structural design around a wheel shaft, while surely performing braking to a support of a composite wheel and grounding wheels.

This brake 120 is a brake to the composite wheel 110 having the support 111 journaled to the wheel shaft 101, and a plurality of grounding wheels 112 rotatably journaled to the support around the wheel shaft. The brake has braking means 121, 122 and 124 for realizing a non-braking state unengaging with the support and the grounding wheels, a first braking state of engaging with the support and a second braking state of engaging with the grounding wheels, and an opening part 111d arranged in the support, insertably constituting at least a part 124 of the braking means and facing the grounding wheels. The brake is characterized by being constituted so that at least a part of the braking means brakes the grounding wheels by inserting the opening part in the second braking state.