In an image processing apparatus that processes image data containing a distortion of an image pickup optical section, which is obtained by picking up an optical image from a subject through the image pickup optical section giving the distortion, a region selection mode setting section (13b) selectively sets a first region selection mode in which, from a field of view represented by the image data, a selected region is selected which indicates a partial region of the field of view by using an orthogonal coordinate system and a second region selection mode in which, from the field of view represented by the image data, the selected region is selected which indicates the partial region of the field of view by using a polar coordinate system. A distortion correction section (13a) corrects the distortion contained in the image data that corresponds to the selected region selected the first or second region selection mode selected in the region selection mode setting section (13b). A data output section (13d) outputs distortion-corrected data.