An imaging lens includes, in sequence from the object side to the image
plane side: a first lens with a convex object side surface and having a
positive overall index of refraction; an aperture stop having a
predetermined diameter; a second lens with a convex object side surface
and having an overall positive index of refraction; and a third lens with
a concave object side surface and an overall negative index of
refraction. At least one surface of the first lens is formed as an
aspherical surface. Both surfaces of the third lens are formed as
aspherical surfaces, with the image side surface having an inflection
point at which the curvature of the surface changes within the effective
diameter range. The imaging lens provides superior optical
characteristics and is compact and suited for use in mobile cameras
installed in portable telephones, PDAs, and the like.