To sufficiently utilize an optical device and optical equipment such as a lens device using the optical device while removing a foreign matter such as dust and waterdrops adhering to the outer surface of the optical device without adversely influencing the performance of the optical device however often they are used.

The waterdrop adhesion preventing device of the optical device is equipped with a rotational holding means including a filter holding ring 16 concentrically holding a filter 14 being a kind of optical device exposed to external space, and a filter coupling ring 18 concentrically rotatably holding the ring 16 through a rotational supporting means 20 such as a ball bearing mechanism, for example; and a rotational driving means including a rotational driving source 24 such as a motor for rotating the ring 16 of the rotational holding means through an output gear 28 meshed with the internal gear 22 of the ring 16 and a gear accelerating mechanism 26.