Imaging lens

An imaging lens comprising:

• a first lens having positive refractive power;
• a second lens;
• a third lens having positive refractive power;
• a fourth lens;
• a fifth lens;
• and
• a sixth lens having negative refractive power, arranged in this order from an object side to an image plane side,
• wherein said second lens has a convex surface facing the object side at a paraxial region thereof,
• said third lens has a convex surface facing the image plane side at a paraxial region thereof,
• said sixth lens has a convex surface facing the image plane side at a paraxial region thereof, and
• said first lens is arranged so that a surface thereof on the object side is away from an image plane by a distance La on an optical axis thereof, and said fourth lens is arranged to be away from the fifth lens by a distance D45 on an optical axis thereof so that the following conditional expressions are satisfied:
• 1.2<La/Hmax <1.8,
• 0.04<D45/f<0.5,
• where f is a focal length of a whole lens system, and Hmax is a maximum image height of the image plane.