In an image pickup unit, a first optical system holding frame has a hole axis orthogonal to an optical axis of photographing light made incident on a first object lens group, and a through-hole portion through which a second optical system holding frame can be inserted and arranged is formed in the first optical system holding frame and the first optical system holding frame and the second optical system holding frame are set relatively movable in a direction orthogonal to the optical axis of the photographing light made incident on the first object lens group and the second optical system holding frame and a third optical system holding frame are set relatively movable in a direction along the optical axis of the photographing light made incident on a solid-state image pickup device such that predetermined optical performance adjustment can be performed during assembly.