A radiation image processing apparatus is provided with a defect detecting device to receive first image data from a sensor which comprises plural elements arranged two-dimensionally, converts irradiated radiation into electric image signals by the plural elements and outputs image data in which each element outputs an image datum of a single pixel, the defect detecting device to detect an image defect in the first image data and to produce defect information indicating a position of the image defect; a memory to store the defect information; and a correcting device for receiving second image data outputted from the sensor on a condition that the sensor is irradiated with radiation passing through an object, for correcting the second image data on the basis of the defect information read out from the memory, and for producing third image data.