1. An X-ray inspecting apparatus, forming images of X-ray transmitted through an area of inspection of an object on a plurality of detection surfaces, for executing a process of reconstructing an image of the area of inspection, comprising: a plurality of X-ray detectors smaller in number than the detection surfaces, configured to pick-up images on said plurality of detection surfaces; a detector driving unit configured to drive some of said plurality of X-ray detectors and remaining ones of said plurality of X-ray detectors independently from each other; an X-ray output unit configured to output X-ray such that the X-ray transmitted through said area of inspection enters said plurality of X-ray detectors moved to a plurality of image pick-up positions as said detection surfaces; and a control unit configured to control an operation of said X-ray inspecting apparatus; wherein said control unit includes: an image acquisition control unit configured to control timing of exposure by each of said X-ray detectors and said detector driving unit, an X-ray output control unit configured to control said X-ray output unit, and an image reconstruction processing unit configured to reconstruct image data of said area of inspection, based on data of intensity distribution of X-ray transmitted through said area of inspection, picked-up at said plurality of detection surfaces; and said image acquisition control unit and said X-ray output control unit configured to execute, in parallel, a process of image pick-up by said some of said plurality of X-ray detectors at a first position among said plurality of image pick-up positions, and a process of moving said remaining ones of said plurality of X-ray detectors to a second position different from said first position among said plurality of image pick-up positions.