A two-unit zoom lens system which forms an image on an image pickup surface, includes in order from an object side to an image side, a first lens unit G1 having a negative refracting power and a second lens unit G2 having a positive refracting power. At the time of zooming from a wide angle end to a telephoto end, a distance between the first lens unit and the second lens unit is narrowed. The first lens unit includes in order from the object side to the image side, a first lens having a negative refracting power, a second lens having a negative refracting power, and a third lens having a positive refracting power, and the two-unit zoom lens system satisfies predetermined conditional expressions.