PROBLEM TO BE SOLVED: To prevent image quality from being degraded due to use of pixels in radiation dose detection with a simple configuration and process of a radiation image detection device.SOLUTION: An FPD 35 includes a composite pixel 58 consisting of a main pixel 58a and a sub-pixel 58b. Simultaneously when X-ray radiograph starts, a TFT 60b of the sub-pixel 58b of the composite pixel 58 within a lighting field is turned on. Electric charges are accumulated in a pixel 36, the composite pixel 58 outside the lighting field, and the main pixel 58a of the composite pixel 58 within the lighting field. AEC is executed in which a radiation dose detection signal based on the electric charge from the sub-pixel 58b and an irradiation stop threshold are compared, and when a target radiation dose is reached, X-ray irradiation is stopped. After X-ray irradiation has stopped, the FPD 35 is driven to execute a readout operation, and an image signal is thereby output. The image signal of the main pixel 58a of the composite pixel 58 within the lighting field is corrected by multiplying it by a ratio of the total aperture area of the composite pixel 58 to the aperture area of the main pixel 58b in a multiplication circuit 68. The corrected image signal and the image signal of the pixel 36 and the composite pixel 58 outside the lighting field are used to generate an X-ray image.
