Provided are a method and apparatus for decoding a mixed code that is a combination of first and second code images. In the method, a mixed code image is obtained by receiving the original image having the mixed code image and removing noise from the original image. Next, the colors, shades, and brightnesses of pixels of the mixed code image are categorized into groups based on a predetermined threshold, the mixed code image is divided into first and second code images, and first and second information are extracted by decoding the first and second code images, respectively. The first and second code images can be effectively decoded by decoding interpretation information, construction information, error control information, and code direction information stored in the first and/or second code images.