Imaging lens

An imaging lens comprising:

• a first lens having positive refractive power;
• a second lens having at least one aspheric surface;
• a third lens having at least one aspheric surface;
• a fourth lens having at least one aspheric surface;
• a fifth lens having at least one aspheric surface;
• a sixth lens having two aspheric surfaces;
• and
• a seventh lens having negative refractive power and two aspheric surfaces, arranged in this order from an object side to an image plane side,
• wherein said first lens is formed in a shape so that a surface thereof on the object side is convex near an optical axis thereof,
• said sixth lens is formed in a shape so that a surface thereof on the image plane side is concave near the optical axis, and
• said first lens has an Abbe's number νd1, said second lens has an Abbe's number νd2, and said fourth lens has an Abbe's number νd4 so that the following conditional expressions are satisfied:
• 40<νd1<75,
• 20<νd2<35,
• 40<νd4<75.