A radiation imaging apparatus that captures radiographic images includes a radioactive ray generating unit configured to irradiate a subject with a plurality of radioactive rays generated by a plurality of electron sources. A radioactive ray detection unit captures a plurality of first radiographic images based on detection of the plurality of radioactive rays that have passed through the subject at different irradiation angles. Area specification unit specifies an object area using the plurality of first radiographic images captured by the radioactive ray detection unit, and a determination unit determines an electron source to be driven from the plurality of electron sources based on the object area specified by the area specification unit, such that a second radiographic image is captured based on the radioactive rays generated by the electron source determined by the determination unit.