The object of the present invention is to provide a radioactive-ray image tube having less deformations, such as the twist of an input substrate, less aberration over the entire regions of an output image, excellent resolution and good brightness uniformity and contrast characteristics. This radioactive-ray image tube 1a comprises an input window 10 formed on one side surface of a vacuum vessel 2a and allowing radioactive-rays to enter the vacuum vessel 2a, an input screen 5 for converting the radioactive-rays incident on the input window 10 into a fluorescent image or a photoelectric image, and an input substrate 4a holding the input screen 5, is characterized in that the input substrate 4a comprises of a clad material 13 having an aluminum alloy material 11 on the radioactive-ray incidence side and a pure aluminum material 12 on the input screen 5 side provided integrally with each other.