The present invention relates to a data processing apparatus for a camera in which correction data for shading correction or the like is stored in a memory and an output formed by a photo-taking information forming circuit such as a sensor and the correction data are operated to thereby accomplish the photo-taking processing on the basis of the operational output. When the data stored in the memory is read out and the operation processing is effected, if an error is contained in the read-out data, the data is subjected to revision processing to thereby correct the error, and then the operation processing is accomplished.