An image inspection system includes a mount stage for a subject; an observation optical system for imaging light reflected by the subject; a focal position moving mechanism for relatively moving a position of the observation optical system in a depth direction of focus with respect to the subject; a mechanism for detecting a first target focal position by using light reflected by the subject; a focal position correcting device for determining a second target focal position offset from the first target focal position; a device for driving the focal position moving mechanism so as to focus on the second target focal position; and a section for storing condition setting data for each subject, which includes an offset value for determining the second target focal position. The focal position correcting device determines the second target focal position in accordance with the offset value in the condition setting data.