PROBLEM TO BE SOLVED: To provide an electronic cassette and an electronic cassette operation method that can allow a short rise time after battery replacement.SOLUTION: An electronic cassette 10 comprises a main battery 19 removably attached to a battery attachment part 36, and a sub-battery 20 for supplying electric power to a bias power supply circuit 50 and the like in place of the main battery 19. A supply source controller 70 switches the supply source of the electric power from the main battery 19 to the sub-battery 20 when determining that a replacement work of the main battery 19 is started. Because the electric power is continuously supplied to the bias power supply circuit 50 and a bias voltage is seamlessly applied to a photo-electric converter 44, there is no need for stabilization of the photo-electric converter or detection of an offset-correcting image after the main power supply is turned on, thus substantially shortening a rise time TR2.SELECTED DRAWING: Figure 11COPYRIGHT: (C)2018,JPO&INPIT
