To provide a Gauss type photographing lens whose image surface is flat from the center to an off-axis peripheral viewing angle and which has high performance while securing production propriety including cost by disposing the positive, the positive and the negative lenses of a front group and the negative, the positive and the positive lenses of a rear group without having a bonded surface while putting a diaphragm in between and making the lens satisfy specified conditional expressions.

This Gauss type photographing lens is constituted by disposing the front group I consisting of 1st to 3rd lenses (L1 to L3) and the rear group II consisting of 4th to 6th lenses (L4 to L6) without having the bonded surface while putting the diaphragm 2 in between. The lens satisfies the conditional expressions (1) to (5). (1) 2.6<;(N1-N2)/(N3-N2)<;4.3, (2) 1.0<;R4/f<;2.3, (3) 1.0<;R4/R5<;1.3, (4) -3.5<;R10/f<;-1.4, (5) 1.1<;R9/R10<;1.6 (N1: the refractive index of L1, N2: the refractive index of L2, N3: the refractive index of L3, R4: the radius of curvature of the surface on an image surface side of L3, R5: the radius of curvature of the surface on the image surface side of L3, R9: the radius of curvature of the surface on the image surface side of L4, R10: the radius of curvature of the surface on an object side of L4, and (f): the focal distance of a lens entire system).