A radiation image capturing apparatus, comprising a sensor configured to monitor an irradiating dose of radiation, a switch configured output a sensor signal from the sensor, a readout unit configured to read out the sensor signal via a signal line, and a controlling unit, wherein the controlling unit performs first control of repeatedly performing, while the sensor is irradiated, a series of operations including a first operation of setting the switch to a conductive state and a second operation of setting the switch to a non-conductive state, second control of reading out the sensor signal in the first operation as a first signal and a potential of the signal line in the second operation as a second signal, and third control of calculating the irradiating dose of radiation based on the first signal and the second signal.