Disclosed are a brake apparatus, a wheel body assembly, and a rollator. The brake apparatus comprises a shaft body, a housing, a magnetic induction mechanism and an adjustment mechanism. The housing rotates relative to the shaft body; the magnetic induction mechanism is arranged in the housing to generate resisting force opposite to a rotation direction of the housing or the shaft body to the housing or the shaft body by a magnetic field reaction when the housing rotating relative to the shaft body. The adjustment mechanism is connected to the magnetic induction mechanism for adjusting a magnitude of the resisting force. The magnetic induction mechanism is capable of playing a braking role on the wheel body integrated or connected with the brake apparatus, because its braking force is related to the rotation of the housing or shaft body, rather than friction braking, it will not produce an emergency stop effect.