An endoscope objective lens unit 1 includes a front lens group FL and a rear lens group RL with an aperture stop STO interposed therebetween. The front lens group FL includes a first lens L1 having a negative refractive power and a second lens L2 having a positive refractive power, and the rear lens group FL includes a third lens L4 having a positive refractive power, and a fourth lens L5 having a positive refractive power and a fifth lens L6 having a negative refractive power, the fourth lens and the fifth lens being cemented to each other. The endoscope objective lens unit satisfies following expressions (1) to (4): (1) -6 < SF < 0 (2) -3 < Fr/Ff < -1.1 (3) -1.6 < Ff/f < -0.6 and (4) Ff/fl < 1.6, where SF is a shape factor, in which R1 is an object-side radius of curvature of the second lens L2 and R2 is an image-side radius of curvature of the second lens L2, Ff is a focal length of the front lens group FL, Fr is a focal length of the rear lens group RL, f is a focal length of the entire unit, and fl is a focal length of the first lens L1.
