An imaging apparatus includes a detector including multiple pixels arranged in a matrix. The detector performs an image capturing operation whereby light or radiation incident on the pixels is converted into an image signal. The imaging apparatus also includes a bias light source and a control unit. The image capturing operation includes a first image capturing operation in which the detector is scanned in a scanning area A and a second image capturing operation in which the detector is scanned in a scanning area B larger than the scanning area A. The control unit controls the bias light source to emit bias light on the basis of a control signal indicative of an amount of integration of accumulation times in the first image capturing operation during a period between the first and second image capturing operations in accordance with switching from an irradiation field A to an irradiation field B.