An image acquisition device comprising: a first X-ray source configured to apply X-rays having a first focal point size; a first detector configured to detect X-rays applied from the first X-ray source and having passed through a measured object; a first image generation means configured to generate a first X-ray CT image, based on the X-rays detected by the first detector; a second X-ray source configured to apply X-rays having a second focal point size smaller than the first focal point size; a second detector configured to detect the X-rays applied from the second X-ray source and having passed through the measured object; a second image generation means configured to generate a second X-ray CT image, based on the X-rays detected by the second detector; and an image correction means configured to correct the first X-ray CT image generated by the first image generation means, based on the second X-ray CT image generated by the second image generation means; further characterised in that: the image correction means is configured to correct the first X-ray CT image so as to converge a sinogram of the first X-ray CT image generated by the first image generation means to a sinogram of the second X-ray CT image generated by the second image generation means; and in that: the first X-ray source is a micro X-ray source and the first focal point size is 1μm to 1 mm, and the second X-ray source is a nano X-ray source and the second focal point size is 1 to 800 nm. a first X-ray source configured to apply X-rays having a first focal point size; a first detector configured to detect X-rays applied from the first X-ray source and having passed through a measured object; a first image generation means configured to generate a first X-ray CT image, based on the X-rays detected by the first detector; a second X-ray source configured to apply X-rays having a second focal point size smaller than the first focal point size; a second detector configured to detect the X-rays applied from the second X-ray source and having passed through the measured object; a second image generation means configured to generate a second X-ray CT image, based on the X-rays detected by the second detector; and an image correction means configured to correct the first X-ray CT image generated by the first image generation means, based on the second X-ray CT image generated by the second image generation means; further characterised in that: the image correction means is configured to correct the first X-ray CT image so as to converge a sinogram of the first X-ray CT image generated by the first image generation means to a sinogram of the second X-ray CT image generated by the second image generation means; and in that: the first X-ray source is a micro X-ray source and the first focal point size is 1μm to 1 mm, and the second X-ray source is a nano X-ray source and the second focal point size is 1 to 800 nm. the image correction means is configured to correct the first X-ray CT image so as to converge a sinogram of the first X-ray CT image generated by the first image generation means to a sinogram of the second X-ray CT image generated by the second image generation means; and in that: the first X-ray source is a micro X-ray source and the first focal point size is 1μm to 1 mm, and the second X-ray source is a nano X-ray source and the second focal point size is 1 to 800 nm.