A radiation imaging apparatus irradiates a subject with a radioactive ray emitted from a radiation generation unit to capture a radiographic image based on a radioactive ray that has penetrated through the subject. The radiation imaging apparatus includes a histogram calculation unit configured to calculate a histogram resulting from pixel values of the radiographic image, and a radiation irradiation condition determination unit configured to determine radiation irradiation conditions for a radioactive ray to be emitted from the radiation generation unit in such a way as to flatten a distribution of the histogram.