PROBLEM TO BE SOLVED: To provide a technique advantageous for highly accurate AEC in a radiation imaging device.SOLUTION: A radiation imaging device 100 includes multiple pixels PX_A each including a detecting element S and a switch element W, signal lines LC1-6, J2, 3, 5, 6 propagating signals outputted from the detecting element S in response to the switch element W becoming conductive, and a control section 140. The control section 140 acquires the signals of the signal lines, when the switch element W is in non-conductive state and in conductive state, respectively, as a first signal and a second signal before stating irradiation of a radiation ray, monitors the signals on the signal lines, before the non-conductive state and in the conductive state, respectively, as a third signal and a fourth signal in response to start of irradiation of a radiation ray, and performs automatic exposure control (AEC) based on the first through fourth signals.SELECTED DRAWING: Figure 1【課題】放射線撮像装置におけるＡＥＣの高精度化に有利な技術を提供する。【解決手段】検知素子Ｓと、スイッチ素子Ｗとからなる複数の画素ＰＸ＿Ａと、スイッチ素子Ｗが導通状態になったことに応じて検知素子Ｓから出力された信号を伝搬する信号線ＬＣ１～６、Ｊ２、３、５、６と、制御部１４０とを備える放射線撮像装置１００である。制御部１４０は、放射線の照射の開始前に、スイッチ素子Ｗが非導通状態およびスイッチ素子が導通状態での信号線の信号をそれぞれ第１信号および第２信号として取得し、放射線の照射が開始されたことに応答して、スイッチ素子が非導通状態前およびスイッチ素子が導通状態での信号線の信号をそれぞれ第３信号および第４信号としてモニタし、第１～第４信号に基づいて自動露出制御（ＡＥＣ）を行う。【選択図】図１
