An image processing apparatus includes a 2D code detecting unit, a 2D code decoding unit, and an invalidation processing unit. The 2D code detecting unit is configured to detect a 2D code in a document image. The 2D code decoding unit is configured to try to decode the detected 2D code. The invalidation processing unit is configured to perform invalidation of the 2D code so as to make this 2D code undetectable by the 2D code detecting unit if the 2D code decoding unit failed to decode the 2D code.