A radiation conversion device, which is driven by an on-board battery, detects radiation that has passed through a subject and converts the radiation into image information. The radiation conversion device includes a battery residual charge amount detector for detecting a residual charge amount of the battery, a transmission rate setting unit for setting a transmission rate of the image information corresponding to the residual charge amount of the battery, and a transmitting unit for transmitting the image information to an external apparatus by means of wireless communications at the set transmission rate.