An apparatus and a method for correcting image data detected by an image sensor with less used memory space and fewer arithmetic operation executions is provided for. A data correcting apparatus of the present invention comprises an operation memory for storing expansion coefficient array data and basis function array data, which includes data of expansion coefficients and function values of a basis function for orthogonally expanding a high order polynomial for correcting input image data; and an operation part for correcting the input image data using the expansion coefficient array data and the basis function array data. With the use of the apparatus, the processing time of the operation part can also be minimized.