In a zoom lens comprising a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power and a fourth lens unit having positive refractive power in order from the object side to the image side, and performing zooming by changing the intervals between the lens units, the third lens unit is constituted by a first lens sub-unit and a second lens sub-unit in order from the object side to the image side, and an image formed by the zoom lens system is displaced by the movement of the second lens sub-unit so as to have a component in the direction perpendicular to the optical axis. Moreover, the first lens sub-unit and the second lens sub-unit constituting the third lens unit are set to positive refractive power, the first lens sub-unit is constituted by a positive lens and a negative lens and the second lens sub-unit is constituted by one lens component.