A radiation image capturing system includes a radiation image capturing apparatus, an irradiation apparatus and an image processing apparatus. The image processing apparatus generates a first radiation image of a subject based on a signal value generated by the radiation image capturing apparatus with no grid attached irradiated by the irradiation apparatus； performs a low-pass filter process on a pixel value of the first radiation image using a scattering kernel, thereby generating a low frequency image； estimates a body thickness of the subject based on the signal value； estimates a scattered ray content rate based on the body thickness； calculates a scattered ray component in the first radiation image based on the low frequency image and the scattered ray content rate； and subtracts the scattered ray component from the first radiation image, thereby generating a second radiation image.
