A radiation imaging apparatus comprises a read unit reading electric signals from radiation detecting elements that are arranged two-dimensionally and that convert incident radiation into electric signals. A control unit controls the radiation detecting unit such that a first radiation detecting element is switched into a state in which charge generated therein cannot be taken out (a "senseless state") and a second radiation detecting element is switched into a state in which it charge generated therein by incident radiation can be taken out (a "sensible state"), and a signal processing unit performs a subtraction processing such that the electric signal from the radiation detecting element that is in the senseless state is subtracted from the electric signal from the radiation detecting element that is in the sensible state, to reduce conspicuous line noise in an image by means of a relatively simple configuration.