The present invention relates to a collapsible type optical unit capable of moving its optical
system between a working position and a retracted position as well as an image-
pickup apparatus including the optical unit. Particularly, the present invention relates to the optical unit and the image-
pickup apparatus capable of acquiring lens-position information by detecting a position of a lens
barrel supported to be movable with respect to a fixed
barrel. The optical unit according to the present invention is a collapsible type optical unit including: a second group lens frame movable along the direction of its
optical axis with respect to a fixed ring and a rear
barrel, and a
solid-state image-
pickup device provided behind the second group lens frame, in which on the movable second group lens frame, a position-detecting means for detecting a position of the second group lens frame is provided. According to the present invention, projection and the like on the exterior portion can be eliminated to be small in size and an increase of the number of parts and the number of processes can be restricted to the minimum.