A radiographic image detecting apparatus and a radiographic image capturing system are provided. The radiographic image detecting apparatus includes a plurality of photoelectric conversion elements for generating electric charge by emission of radiation, a bias line through which a bias voltage is supplied to the photoelectric conversion elements, a power supply for applying the bias voltage to the photoelectric conversion elements through the bias line, a current detector for detecting a bias current flowing through the bias line, and a reading circuit including an amplifying circuit. The current detector includes a current mirror circuit connected between the bias line connected to the photoelectric conversion elements and the power supply.