The present invention provides a technology by which a high quality monochromatic image without any picture quality deterioration can be obtained from a color image original. An image processing apparatus according to the present invention, comprising: a hue information acquiring portion adapted for acquiring hue information regarding pixels forming an image; a concentration information acquiring portion adapted for acquiring hue concentration information regarding pixels forming the image; and a deterioration determining portion, wherein, in the event that a rate of the number of pixels having the same hue and color concentration as those of pixels forming the image is higher than a predetermined threshold value based on the hue information and the hue concentration information thus acquired, the deterioration determining portion is adapted for determining the possibility of occurrence of picture quality deterioration to be high when the image is transformed into a monochromatic image.