To provide the subject non-destructive inspection apparatus capable of efficiently inspecting and observing an object to be inspected in a non- destructive manner.

An non-destructive inspection apparatus of a thin object consists of a soft X-ray source 1 for generating soft X-rays, a vacuum box 9 having soft X-ray windows 11, 12 permitting soft X-rays 2 to pass provided on the inlet and outlet sides thereof, the fluorescent body 10 provided on the downstream side of the vacuum box 9 and an X-ray image processor C. An object S to be inspected is positioned between the soft X-ray window 12 on the outlet side and the fluorescent body 10 to be inspected.