This paper focuses on an extremely rare case: knowledge transfer under a short-distance relocation of a mother factory. The case involves HORIBA Ltd., which relocated its domestic mother factory from Kyoto to Shiga in October 2015. The two locations are close to each other both geographically and culturally. Therefore, conventional wisdom would dictate that knowledge transfer would also be smooth. As it turned out, however, the relocation resulted in an increase in the defect rate because of insufficient knowledge transfer at the time of the relocation. Thus, this paper clarifies the relationship between this problem and the process of knowledge transfer, and identifies the type of knowledge that is difficult to transfer and is important for solving the quality problem. As a result of this detailed analysis, it was suggested that the key to solving the problem is the presence of technical experts who are familiar with how production was handled prior to the relocation, before there were any defect issues.