To shorten the whole length of a whole lens system and also reduce a manufacturing sensitivity, and to improve the optical performance.

The imaging lens includes in order from an object side: a first lens of positive refractive power; an aperture diaphragm for controlling a light amount; a second lens of negative refractive power with a concave face directed to the object side; a third lens of positive refractive power with a concave face directed to the object side; and a fourth lens of negative refractive power. The imaging lens is constituted to satisfy the following conditional expressions (1): f2/f-1.5 and (2): 12228.