To obtain a projection lens which is formed so that the outside diameter of a 2nd lens group is made small and interference with illumination luminous flux is extremely reduced while making an optical system compact, whose resolution is high and whose viewing angle is wide by disposing a diaphragm in the vicinity of the surface of a lens closest to a light source.

This projection lens is constituted of two groups and six lenses. A 1st lens group G1 provided with negative refractive power as a whole and a 2nd lens group G2 obtained by arranging a positive, a positive, a negative and a positive lenses in this order from the screen side and provided with positive refractive power as a whole are arranged in this order from the screen side. Besides, the diaphragm 2 is disposed at a position within 0.5f [(f) is the focal length of the total lens system] from the surface of the lens closest to the light source.