Provided is a radiation imaging system with good usability and capable of accurately halting a series of processing steps when the radiation imaging system erroneously detects the start of radiation. This radiation imaging system (100) is provided with a transportable radiation imaging device (1), a radiation generating device (52), a console (60), and a portable terminal (70). If data for use in a preview image has been transmitted from the radiation imaging system (1) before a completion signal has been transmitted from the portable terminal (70), then the console (60) transmits a cancel signal to said radiation imaging device (1), stops processing taking place in the radiation imaging device (1) and resumes processing for reading leak data (dleak) before the radiation imaging further, if data for use in a preview image has been transmitted from the radiation imaging device (1) after the completion signal has been transmitted from the portable terminal (70), the console (70) generates a preview image (p_pre) on the basis of said data for use in a preview image.