Imaging lens

An imaging lens comprising:

• a first lens having positive refractive power;
• a second lens;
• a third lens;
• a fourth lens having negative refractive power;
• a fifth lens having positive refractive power;
• and
• a sixth lens, arranged in this order from an object side to an image plane side,
• wherein said second lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side have positive curvature radii,
• said fourth lens is formed in a shape so that a surface thereof on the image plane side has a negative curvature radius, and
• said sixth lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side have positive curvature radii.