A radiation imaging apparatus includes a pixel array arranged with a plurality of pixels including conversion units configured to convert radiation into charges and accumulate the charges, a bias line connected to the conversion units of the plurality of pixels, a bias circuit configured to supply a bias potential to the bias line and detect a current flowing in the bias line, a noise reduction circuit configured to reduce, separately from the bias circuit, noise included in the bias potential from the bias circuit, and a switch configured to connect the noise reduction circuit to the bias line.