To inexpensively and easily produce an objective lens for endoscope having the wide angle of visibility, and to efficiently and easily perform various kinds of observation and operation by using an endoscope.

This lens is constituted by combining a single plane-convex lens 10 having a homogenous refractive index and a single refractive index distribution lens 12 having refractive index distribution in a radial direction, which are arranged along an optical axis in such order as an object surface, the homogenous plane-convex lens, the refractive index distribution lens and an image surface. Both surfaces of the refractive index distribution lens are plane and the homogenous plane-convex lens is set so that its convex surface faces to the refractive index distribution lens side and its plane surface faces to the object side. By regulating the characteristics of the refractive index distribution lens and the homogenous plane-convex lens, it is possible to set the angle of visibility to ≥50°.