The invention provides an image processing device, an imaging device, an image processing method, and a non-transitory computer readable recording medium recorded with an image processing program that can instantaneously correct shading characteristics. A correction unit calculates a shading characteristic correction coefficient based on a first comparison result and a second comparison result and corrects the shading characteristics of a subsequent frame based on the calculated coefficient. The first comparison result indicates the result of the comparison between a phase difference image and a normal image included in a preceding frame acquired first a pair of frames acquired at different times. The second comparison result indicates the result of the comparison between a phase difference image and a normal image included in the subsequent frame. A control unit directs a display device to continuously display the subsequent frame, of which the shading characteristics have been corrected, as a moving image.