PROBLEM TO BE SOLVED: To provide a low cost endoscope system capable of providing an image of high quality in which a depth of field is enlarged, in consideration of a production error of components.SOLUTION: An endoscope system includes an objective optical system, an optical path dividing part for dividing a subject image acquired by the objective optical system into two optical images with different focuses, an image pickup device for acquiring the optical images, and an image composition processing part for selecting images with relatively high contrast in a predetermined area of the acquired two optical images and generating a composite image. The optical path dividing part composed of two prisms causes the two optical images with a desired difference in the optical path length to be formed on one image pick-up device by a prism driving part that performs optical path length difference adjustment by changing the relative positional relationships of the two prisms, satisfying the following conditional expression (1) and (2): (1) 0.01
