Provided are a defogging system and a defogging method. The defogging system includes: an illuminance sensor configured to detect a surrounding illuminance; a level determiner configured to determine a defogging level of the input image based on the detected surrounding illuminance; and a defogger configured to determine a fog state of the input image based on a histogram of the input image, and adaptively defog the input image according to the determined fog state and defogging level.