1. A radiation imaging apparatus comprising: radiation detection means including radiation detection elements for detecting radiations which have penetrated an object as electric signals, said elements arranged in a two-dimensional array; and image display control means for producing a radiation image of the object detected as the electric signals with said radiation detection means as continuous images including a plurality of frames, said image display control means switching a tube voltage of a radiation source for emitting the radiations between a voltage at a time of producing a (2m−1)th odd image and another voltage at a time of producing a 2mth even image, where m is a natural number, said image display control means further controlling a display device to display a processed image as a dynamic image, the processed image being obtained by performing a subtraction process between the (2m−1)th odd image and the 2mth even image.