This X-ray exposure control device includes: an X-ray detection element (18) provided with a plurality of dose-detecting pixels (76) for detecting the dose in X-ray irradiation; a region-setting unit (86) for setting a usage pixel region comprising dose-detecting pixels (76) to be used, from among the plurality of dose-detecting pixels (76), in X-ray irradiation; a signal generation unit (90) for generating an X-ray irradiation stop signal in accordance with the detected dose of the dose-detecting pixels (76) in the set usage pixel region; and a transmission unit (94) for transmitting the X-ray irradiation stop signal to the X-ray source. The X-ray exposure control device makes it possible to acquire an appropriately dense X-ray image at all times in the same image-capturing environment even when capturing images of a variety of different sites. Provided are an X-ray image detection apparatus including the X-ray exposure control device, and an X-ray image capturing system including the X-ray image detection apparatus.