A radiation image capturing apparatus includes a housing for housing a radiation detector. The housing has a wall inclined with respect to a detection surface of the radiation detector, and the wall defines a space inclined with respect to the detection surface. The space allows heat transfer medium such as air of relatively high temperatures (higher than that of outside air, for example) to rise along a slope defined by the space. If the region around the detection surface is heated to high temperatures, airflow is generated within the space, forcing the relatively high-temperature heat transfer medium away from the vicinity of the radiation detector, thereby allowing the whole radiation detector to be cooled in a uniform manner.