An imaging device capable of obtaining image data with a small amount of X-ray irradiation is provided. The imaging device obtains an image using X-rays and includes a scintillator and a plurality of pixel circuits arranged in a matrix and overlapping with the scintillator. The use of a transistor with an extremely small off-state current in the pixel circuits enables leakage of electrical charges from a charge accumulation portion to be reduced as much as possible, and an accumulation operation to be performed substantially at the same time in all of the pixel circuits. The accumulation operation is synchronized with X-ray irradiation, so that the amount of X-ray irradiation can be reduced.提出一種能夠以少量的X光照射來獲得影像資料的成像裝置。成像裝置使用X光來獲得一影像且包括一閃爍器及複數個像素電路，排列成一矩陣並與閃爍器重疊。在像素電路中使用具有極小截止電流的電晶體使來自一電荷累積部的電荷之洩漏能盡可能地降低，且一累積操作在所有像素電路中能實質上同時地進行。累積操作與X光照射同步，使得X光照射量能降低。
