To provide a zoom lens having a high zoom ratio without a variable diaphragm, and also, reducing the change in F-number in zooming.

The zoom lens includes in order from an enlargement conjugate side to a reduction conjugate side: a negative lens unit having negative refractive power; at least one positive lens unit having positive refractive power; an intermediate lens unit including a diaphragm; and at least one reduction-side lens unit. The negative lens unit, at least two enlargement-side movable lens units in the one positive lens unit, and at least one reduction-side movable lens unit in at least one reduction-side lens unit are moved upon zooming. The zoom lens satisfies the following inequalities: 0.9(XTTbW)/(XWWbT)1.1, 0.9W/T1.1, 0.8(TSTb)/(WSWb)1.2 and 1.4fT/fW.