1. An imaging device comprising: a zoom lens system having a plurality of lens units and forming an optical image of an object so as to continuously optically zoom by varying distances between the lens unit; and an image sensor converting the optical image formed by the zoom lens system to an electric signal, wherein the zoom lens system comprises from an object side: a first lens unit being overall negative and including a reflecting surface that bends a luminous flux substantially 90 degrees; and a second lens unit disposed with a variable air distance from the first lens unit, and having an optical power, and wherein at least one lens element made of resin is included in the entire lens system.