Conventionally, it has been impossible to output an image that allows for an easy and accurate diagnosis as to whether or not a malignant tumor is present and that allows for correctly indicating a part with a high or low grade of malignancy in the tumor. With an image processing apparatus that includes: a receiving unit configured to receive diffusion weighted images； a parameter acquisition unit configured to acquire parameters of two or more types for each of one or more units of processing that constitute the diffusion weighted images, by using the diffusion weighted images； a diagnostic image composition unit configured to acquire, for each of the one or more units of processing, a score that corresponds to the parameters of two or more types, by using the parameters of two or more types, and to compose a diagnostic image that is an image having, for each of the one or more units of processing, a pixel value that corresponds to the acquired score that corresponds to the unit of processing； and an output unit configured to output the diagnostic image, it is possible to output an image that allows for an easy and accurate diagnosis as to whether or not a malignant tumor is present and that allows for correctly indicating a part with a high or low grade of malignancy in the tumor.
