To provide an imaging apparatus which is compact and has a small residual chromatic aberration in spite of the apparatus being equipped with a high-performance and high variable-power zoom lens system.

The imaging apparatus is equipped with the zoom lens system which has a plurality of lens groups and continuously and optically varies the power for an optical image of a body by varying the gaps between the plurality of lens groups and an imaging element which converts the optical image formed by the zoom lens system into an electric signal. The zoom lens system is provided with a 1st lens group which has a positive optical power and is fixed about an image plane in power variation, a 2nd lens group which is arranged on the image side of the 1st group at a variable interval and has a negative optical power, a 3rd lens group which is arranged on the image side of the 2nd group at a variable interval and has a positive optical power, and an image-side group which is arranged on the image side of the 3rd group at a variable interval and comprises at least two lens groups, and further equipped with one diffracting optical surface in the zoom lens system.