A lens unit may include a plurality of lenses; and a lens barrel made of resin and comprising a tube part. A first press-fitted lens of the plurality of lenses may include a first press-fitted portion that is press-fitted to the tube part. An outer peripheral face of the tube part may include a thread groove. The tube part may include a circular groove which is recessed from an image side end face of the tube toward an object side, the circular groove being formed between an inner peripheral face and the outer peripheral face of the tube part. The first press-fitted portion may be provided on an image side end of the first press-fitted lens. An object side end of the circular groove may be disposed on an object side of the first press-fitted portion.