A structure for mounting ancillaries on a vehicle wherein one end of a first bracket in a plate form extends downwardly and is fixed to a body frame and the other end of the first bracket supports a reservoir. In addition, the first bracket supports the regulator in the proximity of the reservoir. The reservoir attached to the forward end of the first bracket functions as a deadweight which, because of the inertia of the deadweight, suppresses the vibrations of the forward end of the first bracket due to vehicle traveling and engine rotation. Thus, this structure suppresses and attenuates the vibration of the regulator attached to the first bracket.