Lens device and imaging apparatus

A lens device, comprising:

• a mount having a contact surface that contacts an exterior member;
• a first optical system including a plurality of lenses;
• a lens holding barrel holding at least one of the plurality of lenses;
• a first drive unit configured to move the lens holding barrel forward and backward along an optical axis of the first optical system;
• a light amount adjustment unit including a second drive unit configured to adjust an amount of light in the first optical system;
• and
• a regulation member including a regulation portion configured to regulate a position of the light amount adjustment unit along the optical axis,
• wherein at least part of the at least one of the plurality of lenses held by the lens holding barrel is disposed on an image plane side relative to the contact surface along the optical axis, and
• wherein the first drive unit, the second drive unit, and the regulation portion are disposed at different positions in a plane orthogonal to the optical axis.