An X-ray imaging apparatus including an X-ray generation means for emitting X-rays, and an X-ray detector on which a grid selected from a plurality of different types of grids is removably mountable. The X-ray detector receives the X-rays emitted from the X-ray generation means, and obtains an X-ray image. The X-ray detector includes an automatic exposure control (AEC) detector for detecting the quantity of X-rays emitted from the X-ray generation means and for outputting a signal based on the detected quantity. The X-ray imaging apparatus also includes a control means for controlling the X-ray generation means and the AEC detector, where the control means controls the X-ray generation means based on the signal output from the AEC detector, and where the control means controls the AEC detector using correction data to correct an exposure detection element forming a part of the AEC detector.