An X-ray image processing apparatus comprising: a correcting unit (234, 235, 236, 237, 238) configured to identify, based on an observation value of a residual contrast material component that is injected to a subject before a predetermined timing and remains in the subject, the residual contrast material component and a new contrast material component that is newly injected to the subject after the predetermined timing regarding a contrast material component that is included in an X-ray image, and corrects an observation value of the contrast material component included in the X-ray image, wherein: The X-ray image is a target image acquired after the predetermined timing and also after the new contrast material is injected in a test in which the contrast material is injected to the subject at a plurality of stages; and the correcting unit (234, 235, 236, 237, 238) comprises: a residual contrast material calculating unit configured to calculate the observation value of the residual contrast material component included in the target image by subtracting an initial image acquired at an initial stage at which an accumulation amount of contrast material injected to the subject in the test is a predetermined amount or less from a pre-injection image acquired after the predetermined timing and before the new contrast material; a total calculating unit configured to calculate a total of the observation value of the residual contrast material component and the observation value of the new contrast material component by subtracting the initial image from the target image; characterised in that the correcting unit further comprises a target image correcting unit configured to correct the observation value of the new contrast material component among contrast material components included in the target image, based on a correction value corresponding to the observation value of the residual contrast material component and based on a further correction value corresponding to the total. The X-ray image is a target image acquired after the predetermined timing and also after the new contrast material is injected in a test in which the contrast material is injected to the subject at a plurality of stages; and the correcting unit (234, 235, 236, 237, 238) comprises: a residual contrast material calculating unit configured to calculate the observation value of the residual contrast material component included in the target image by subtracting an initial image acquired at an initial stage at which an accumulation amount of contrast material injected to the subject in the test is a predetermined amount or less from a pre-injection image acquired after the predetermined timing and before the new contrast material; a total calculating unit configured to calculate a total of the observation value of the residual contrast material component and the observation value of the new contrast material component by subtracting the initial image from the target image; characterised in that the correcting unit further comprises a target image correcting unit configured to correct the observation value of the new contrast material component among contrast material components included in the target image, based on a correction value corresponding to the observation value of the residual contrast material component and based on a further correction value corresponding to the total. a residual contrast material calculating unit configured to calculate the observation value of the residual contrast material component included in the target image by subtracting an initial image acquired at an initial stage at which an accumulation amount of contrast material injected to the subject in the test is a predetermined amount or less from a pre-injection image acquired after the predetermined timing and before the new contrast material; a total calculating unit configured to calculate a total of the observation value of the residual contrast material component and the observation value of the new contrast material component by subtracting the initial image from the target image; characterised in that the correcting unit further comprises a target image correcting unit configured to correct the observation value of the new contrast material component among contrast material components included in the target image, based on a correction value corresponding to the observation value of the residual contrast material component and based on a further correction value corresponding to the total.