A mobile X-ray device 1 is provided with a main body 2 having an X-ray generating part 10 and an image reader 50 for reading X-ray image information from an imaging plate storing the X-ray image information, a running part 60 for running the main body 2, a battery 70 for storing direct current electrical energy to be supplied to the running part 60 and discharging a direct current at a rated voltage of the running part 60, and a direct current power source voltage conversion part 80 for transforming direct voltage of the battery 70 to a rated voltage of the image reader 50, wherein the rated voltage of the image reader 50 transformed by the direct current power source voltage conversion part 80 is applied to the image reader 50.
