To provide a radiation imaging apparatus and a radiation imaging system that can detect radiation with high accuracy, the radiation imaging apparatus includes: a detection unit in which conversion elements that convert radiation into an electric signal are arranged in a matrix shape; a radiation detection unit configured to detect an irradiation state of radiation; a drive circuit configured to drive the detection unit in accordance with the irradiation state detected by the radiation detection unit; and a radiographing kind setting unit configured to set a radiographing kind, wherein the radiation detection unit changes a radiation detection capability in accordance with the radiographing kind set by the radiographing kind setting unit.