<p>The aims of this paper are to take a broader view of R&D from the perspective of patent materials rather than limiting it to the activities of the research department, to clarify the organization of the flows of technological information by the patent department that promoted R&D, and to depict the R&D and corporate growth of Fuji Electric in the 1920s and 1930s, which remains unclear.</p> <p>The characteristics of Fuji Electric’s R&D and patent management were defined by the company’s objective to introduce Siemens-style electrical technology into the Japanese electrical market, which was dominated by American technology, and to domesticate that technology to gain a foothold in the market. Fuji Electric introduced about 3,400 patents from Siemens and invented about 1,100 patents in the interwar period. Comparing this figure to that of the Shibaura Engineering Works, Shibaura introduced about 2,100 patents from GE and invented about 1,500 patents, so Fuji Electric introduced technology on a larger scale than Shibaura’s case. In order to manufacture and sell Siemens-type electrical apparatuses while American technology was dominant, Fuji Electric had to introduce a comparatively large amount of technology and develop its own technology suitable for the Japanese market.</p> <p>The organization of the flows of technical information by the patent department supported technology introduction, R&D, and the establishment of a market position. As part of the process of the applications of Siemens’s patents, the technological information accumulated in the patent department was disseminated to the design department and other related departments within the company. Through the editing and publication of the Fusi Denki Zihô (Fuji Electric Journal), technical information was supplied to the entire company and was shared with the market. This was the patent management established in Fuji Electric in the 1920s and 1930s and was the mechanism that supported the business development.</p>