An exemplary embodiment of the present invention relates to an imaging lens, the imaging lens including, in an ordered way from an object side, a first lens having positive (+) refractive power, a second lens having negative (−) refractive power, a third lens having positive (+) refractive power, a fourth lens having negative (−) refractive power, wherein the imaging lens meets a conditional expression of D4−D3≦0, where D3 is a distance from an apex of an object side surface of the third lens to an apex of an image side surface of the third lens, and D4 is an axial distance from the apex of an object side surface of the third lens to an effective diameter of an object side surface of the fourth lens.