An endoscope system includes an in-focus object plane position switch section that switches an in-focus object plane position of an imaging section, a target in-focus position determination section that calculates an in-focus evaluation value, and determines a target in-focus position based on the in-focus evaluation value, and a change-in-scene detection section that detects whether or not a change in scene has occurred based on a captured image. The target in-focus position determination section determines whether or not the in-focus evaluation value satisfies a determination criterion until the change-in-scene detection section detects that the change in scene has occurred, and selects the first in-focus object plane position or the second in-focus object plane position that is not currently selected by the in-focus object plane position switch section when it has been determined that the in-focus evaluation value does not satisfy the determination criterion.