A radiation image acquiring system that improves the detection accuracy of a foreign substance etc., in a subject is provided. An X-ray image acquiring system 1 irradiates X-rays to a subject S from an X-ray source, and detects X-rays in a plurality of energy ranges transmitted through the subject S. The X-ray image acquiring system 1 includes a low-energy detector 32 for detecting X-rays in a low-energy range that is transmitted through the subject S to generate low-energy image data, a high-energy detector 42 arranged in parallel to the low-energy detector 32 with a dead zone region 82 sandwiched therebetween, for detecting X-rays in a high-energy range that is transmitted through the subject S to generate high-energy image data, and a timing control section 50 for controlling detection timing of the high-energy detector 42 based on a dead zone width NW of the dead zone region 82 so that low-energy image data to be generated by the low-energy detector 32 and high-energy image data to be generated by the high-energy detector 42 mutually correspond.