Imaging lens

An imaging lens comprising:

• a first lens group;
• a second lens group;
• and
• a third lens group, arranged in this order from an object side to an image plane side,
• wherein said first lens group includes a first lens, a second lens, and a third lens having negative refractive power,
• said second lens group includes a fourth lens and a fifth lens having negative refractive power,
• said third lens group includes a sixth lens having negative refractive power and a seventh lens,
• said first lens, said second lens, said third lens, said fourth lens, said fifth lens, said sixth lens, and said seventh lens are arranged with a space between each of the lenses,
• said first lens is formed in a shape so that a surface thereof on the object side has a positive curvature radius, and
• said third lens is arranged to be away from the fourth lens by a distance D34 on an optical axis thereof so that the following conditional expression is satisfied:
• 0.03<D34/f<0.2
• where f is a focal length of a whole lens system.