A radiation image capturing device includes a radiation image capturing unit, a diaphragm unit, and a control unit. The radiation image capturing unit captures a radiation image based on radiation transmitted through a subject. The diaphragm unit has an opening region that is configured to transmit a part of the radiation emitted from a radiation source and an area thereof is changeable, and the diaphragm unit is configured such that a transmission dose of the radiation decreases as a distance from a circumferential part of the opening region increases. The control unit controls the diaphragm unit such that direct rays of the radiation are irradiated onto a predetermined region of the subject.