An X-ray exposure control device which is used in an X-ray image detection apparatus (14, 102, 122) to detect an X-ray image of a radiography target exposed to X-ray radiation from an X-ray source and which controls an accumulated dose of the X-ray radiation received by the radiography target, the X-ray exposure control device comprising: an X-ray detection element (18, 18a, 18b, 18c) including a plurality of pixels for dose detection (76, 76a) each detecting a dose during the X-ray radiation; a region setting unit configured to set a use pixel region including pixels for use in dose detection from the plurality of pixels for dose detection during the X-ray radiation; a storage unit configured to read out the dose detected by each of the plurality of pixels for dose detection in the X-ray detection element at each preset sampling timing during the X-ray radiation, to obtain the accumulated dose by accumulating the dose detected and read out at each preset sampling timing, and to store the accumulated dose as dose information; a signal generating unit configured to read out the accumulated dose from the storage unit, calculate an estimated time at which the accumulated dose reaches a target value and generate a stop signal for stopping the X-ray radiation from the X-ray source when the calculated estimated time is reached; and a transmission unit configured to transmit to the X-ray source the stop signal to stop the X-ray radiation as generated by the signal generating unit, characterised in that the region setting unit is configured to identify subject pixels representing the radiography target constituting a subject or pixels within a radiation field exposed to the X-ray radiation by combining a plurality of pixel characteristics and neighboring pixel characteristics from dose information of the plurality of pixels for dose detection, and set the use pixel region containing the subject pixels or the pixels within the radiation field as the pixels for use in the dose detection. an X-ray detection element (18, 18a, 18b, 18c) including a plurality of pixels for dose detection (76, 76a) each detecting a dose during the X-ray radiation; a region setting unit configured to set a use pixel region including pixels for use in dose detection from the plurality of pixels for dose detection during the X-ray radiation; a storage unit configured to read out the dose detected by each of the plurality of pixels for dose detection in the X-ray detection element at each preset sampling timing during the X-ray radiation, to obtain the accumulated dose by accumulating the dose detected and read out at each preset sampling timing, and to store the accumulated dose as dose information; a signal generating unit configured to read out the accumulated dose from the storage unit, calculate an estimated time at which the accumulated dose reaches a target value and generate a stop signal for stopping the X-ray radiation from the X-ray source when the calculated estimated time is reached; and a transmission unit configured to transmit to the X-ray source the stop signal to stop the X-ray radiation as generated by the signal generating unit, characterised in that the region setting unit is configured to identify subject pixels representing the radiography target constituting a subject or pixels within a radiation field exposed to the X-ray radiation by combining a plurality of pixel characteristics and neighboring pixel characteristics from dose information of the plurality of pixels for dose detection, and set the use pixel region containing the subject pixels or the pixels within the radiation field as the pixels for use in the dose detection.