A radiation imaging apparatus is provided. The radiation imaging apparatus includes a radiation detector including a plurality of detector modules disposed therein, each detector module including a plurality of radiation detecting elements, wherein each of the detector modules includes a temperature sensor. The radiation imaging apparatus further includes an acquiring device configured to acquire temperature characteristic information of sensitivities of the radiation detecting elements from a storing device in which the temperature characteristic information is stored in advance, and a correcting device configured to correct data detected by the radiation detecting elements, based on temperature information acquired by the temperature sensor and the temperature characteristic information acquired by the acquiring device.