In a detection panel, plural pixels which receive X-ray and accumulate electric charge and plural measuring pixels which detect X-ray dose are provided on an imaging surface. The plural measuring pixels are arranged periodically with an interval. In a position facing to the imaging surface, there is a grid where X-ray absorbing sections and X-ray transmitting sections are arranged in a periodic alternating manner in a first direction. Since the arrangement period of the measuring pixels in the first direction is different from a fluctuation period of grid detection signals obtained when the grid is photographed by the detection panel, output values of the plurality of measuring pixels disperse and a fluctuation range of average values is suppressed.
