The objective of this paper is to provide results of a study on verifying the remediation of sand contaminated by LNAPL. The remediation mechanism used was air injection and a micro x-ray computed tomography (CT) scanner was used to show the effectiveness of the mechanism. First, air at 20oC and 60oC was injected into dry sandy soil. Then, the specimen was observed for effluent change. In this paper, the following three items will be shown: 1) development of the test apparatus for fluid injection into the sandy soil, 2) establishing a scan method using a micro-focused x-ray CT scanner and 3) development of a new image processing technique that can evaluate residual fluids in the pore structure of sandy soil.