Micro computed tomography (muCT) is quite useful for quality evaluation of electro-mechanical systems because it provides three-dimensional geometrical information of internal structures. However, large differences in x-ray absorption coefficients of materials produce metal artifacts in the CT images. This study aims to develop a new reconstruction algorithm to reduce the artifacts from the images and establish a non-destructive inspection technique of electro-mechanical systems using x-ray CT imaging. This paper discusses the cause of the artifacts and proposes two algorithms to reduce them. One is direct signal conversion technique of the projection data, and the other uses two projection data based on different x-ray intensities. The authors apply the methods to several samples and discuss the efficiency of the methods.