An X-ray transmission inspection apparatus comprising: an X-ray source configured to irradiate a sample with X-rays; a two-dimensional sensor installed on the opposite side of the X-ray source with the sample placed therebetween and configured to detect X-rays transmitted through the sample; a sample moving mechanism capable of moving the sample at a predetermined speed in a predetermined direction parallel to a detection surface of the two-dimensional sensor during a scan operation; a calculation unit configured to process an image of the X-rays detected by the two-dimensional sensor; and a display unit capable of displaying a cross-sectional image based on the image of the X-rays processed by the calculation unit, wherein the two-dimensional sensor includes a plurality of pixels (3a, 3b, 3c) that are image sensing devices arranged in a lattice pattern and is capable of reading images detected by all of the pixels (3a, 3b, 3c) at once at a predetermined frame rate, wherein the calculation unit creates a cross-sectional image of the sample at a position having a distance of L from the X-ray source by performing an addition process of continuously adding the images of pixels (3a, 3b, 3c) of each frame at [(LS × V1) / (L × F × A)] along the predetermined direction where V1 is the predetermined speed at which the sample moves, F is the predetermined frame rate, A is a pixel pitch of the two-dimensional sensor, and LS is a distance between the X-ray source and the two-dimensional sensor, and wherein the calculation unit performs the addition process for all virtual slices of the sample over the full thickness of the sample while changing the distance of L from the X-ray source to obtain the cross-sectional images of all the virtual slices of the sample, characterized in that the X-ray transmission inspection apparatus further comprises a sample rotating mechanism capable of changing the orientation of the sample with respect to the X-ray source between a first scan operation and a second scan operation, and wherein the calculation unit creates a plurality of cross-sectional images of the sample from X-rays transmitted through the sample from different directions by changing the orientation of the sample by the sample rotating mechanism. an X-ray source configured to irradiate a sample with X-rays; a two-dimensional sensor installed on the opposite side of the X-ray source with the sample placed therebetween and configured to detect X-rays transmitted through the sample; a sample moving mechanism capable of moving the sample at a predetermined speed in a predetermined direction parallel to a detection surface of the two-dimensional sensor during a scan operation; a calculation unit configured to process an image of the X-rays detected by the two-dimensional sensor; and a display unit capable of displaying a cross-sectional image based on the image of the X-rays processed by the calculation unit, wherein the two-dimensional sensor includes a plurality of pixels (3a, 3b, 3c) that are image sensing devices arranged in a lattice pattern and is capable of reading images detected by all of the pixels (3a, 3b, 3c) at once at a predetermined frame rate, wherein the calculation unit creates a cross-sectional image of the sample at a position having a distance of L from the X-ray source by performing an addition process of continuously adding the images of pixels (3a, 3b, 3c) of each frame at [(LS × V1) / (L × F × A)] along the predetermined direction where V1 is the predetermined speed at which the sample moves, F is the predetermined frame rate, A is a pixel pitch of the two-dimensional sensor, and LS is a distance between the X-ray source and the two-dimensional sensor, and wherein the calculation unit performs the addition process for all virtual slices of the sample over the full thickness of the sample while changing the distance of L from the X-ray source to obtain the cross-sectional images of all the virtual slices of the sample, characterized in that the X-ray transmission inspection apparatus further comprises a sample rotating mechanism capable of changing the orientation of the sample with respect to the X-ray source between a first scan operation and a second scan operation, and wherein the calculation unit creates a plurality of cross-sectional images of the sample from X-rays transmitted through the sample from different directions by changing the orientation of the sample by the sample rotating mechanism.