Provided is a portable radiological image capturing apparatus that, even if left uncharged for a relatively long term and can be used for capturing radiological images and maintain the electric POWER required for reading electric signals from radiation detecting elements to obtain radiological images. The portable radiological image capturing apparatus has, as electric POWER supplying modes and an image-capturable mode in which electric powers are supplied to a plurality of functional units and a sleep mode in which electric powers are supplied only to some ones of the functional units. In the portable radiological image capturing apparatus, said some functional units include a wireless communication unit and there are provided a primary battery and a rechargeable secondary battery. In the sleep mode and the wireless communication unit has been activated by the primary battery. Upon reception of a transition signal from an external device, the wireless communication unit activates the secondary battery to supply an electric POWER to a control unit, thereby activating the control unit to cause the secondary battery to supply electric powers therefrom to the plurality of functional units including the wireless communication unit and thereby transitioning the electric POWER supplying mode to the image-capturable mode.
