Provided are an imaging unit capable of reducing a diameter of a distal end of an insertion unit and obtaining a high-quality image, an imaging module, and an endoscope system. An imaging unit 10 according to the present invention includes a semiconductor package 20 which includes an image sensor and where connection electrodes 21 are formed, a circuit board 30 which is connected to the semiconductor package 20 in an f3 face, a deformed circuit board 40 where connection electrodes are formed on at least f5, f6, and f7 faces and which is connected to the circuit board 30 in the f5 face, electronic components 51 and 52 which are mounted on an f4 face of the circuit board 30, and a plurality of cables 60 which are connected to the connection electrodes of the f6 and f7 faces of the deformed circuit board 40. The electronic components 51 and 52 are housed in a recess 43 on the f5 face of the deformed circuit board 40. The circuit board 30, the deformed circuit board 40, and the plurality of cables 60 are located within a projection plane in an optical axis direction of the semiconductor package 20.
