An imaging unit includes: a semiconductor package including an image sensor and a connection electrode; a circuit board including a main body including a connection land, and an attachment portion protruding on a back surface of the main body and including cable connection electrodes formed on at least two opposing side surfaces; electronic components mounted on an electronic component mounting area on the back surface; and cables electrically and mechanically connected to the cable connection electrodes of the attachment portion. The attachment portion protrudes from the main body such that a center plane of the two side surfaces is shifted from a center plane of side surfaces parallel to the two side surfaces, and at least one side surface is perpendicular to the back surface of the main body. The electronic component mounting area is arranged on the back surface of the main body side-by-side with the attachment portion.