A lenses unit for an endoscope includes a lens barrel； a lens serving as a front group lens and lenses serving as a rear group lens, which are housed inside the lens barrel； and an aperture arranged between the front group lens and the rear group lens. An imaging-side final surface of the rear group lens has a structure in which the imaging-side final surface is fixed to a cover glass of an image pickup device with an adhesive layer. A focal distance fF of the front group lens, a focal distance fB of the rear group lens, a focal distance fel of an entire optical lenses group, a total optical length OL of the optical lenses group, and a metal back MB of the optical lenses group satisfy a relationship of fel/fF<；0, fel/fB>；0, and OL/MB>；7.0.
