The purpose of this paper is examine the circumstances under which Mitsui Mining Co. had established Miike Chisso Industries and Toyo Koatsu Industries, in three respects; (1) the relations of the dyestuff industry which Mitsui Mining Co. had developed, to the synthetic ammonia industry, (2) the reasons why it had established two companies of the same type, and (3) the meanings of the merger of Daiichi Chisso Kogyo Co. Mitsui Mining Co. started to produce in Taisho Era various dyestuffs using tar collected from coke ovens. In late 1920's, as the production of alizarin and sulphuric dyestuffs had increaced, the demand of the nitric acid, which is necessary for producing dyestuffs, also increased. So, it caused lack of nitric acid. This condition was critical to Mitsui Mining Co., because it had decided to start producing Indigo. Then, it had to make for itself the nitric acid from the synthetic ammonia. On the other hand, having established Miike Chisso Industries, Mitsui Mining Co. set up Toyo Koatsu Industries in order to introduce a new method of the synthetic ammonia, to produce the ammonium-sulphate which were then insufficient in Japan, and to supply Miike Senryo Kogyosho (Miike Dyestuff Works), which belonged to Mitsui Mining Co., with the ammonia to produce the nitric acid. The true reason why it didn't enlarge Miike Chisso Industries but established Toyo Koatsu Industries was to intend tax exemption. So, after the expiration of the special privilege, they were amalgamated. The most difficult and also important problems to produce the synthetic ammonia were to select the technology they shoud adopt and to obtain related skilled engineers, in those days. Mitsui Mining Co. solved these problems by merging Daiichi Chisso Kogyo.
Nippon Electric Power Co. Ltd. (Nippon Denryoku) was founded after World War 1 as a subsidiary of Ujigawa Electric Power Co. Ltd. (Ujigawa Denryoku), with the intention that its main business would be the supply of wholesale electricity to Ujigawa. However, Ujigawa decided to go into partnership with, and to buy electricity from, Great Consolidated Electric Power Co. Ltd. (Daido Denryoku), which had completed electric power transmission facilities to Osaka before Nippon Electric, and so Nippon Electric lost its largest customer. It was forced to seek other purchasers for its electricity to replace Ujigawa and, undertaking a positive sales drive, found customers in Osaka, Hyogo, Kyoto, Aichi and Toyama Prefectures. As a result of this Nippon Electric was able to break away from its parent company and become independent. The main reasons for its growth were the low price of the electricity it supplied and the rapid expansion of the power supply market in the 1920s caused by the electrification of industry. However, in the process of becoming independent Nippon Electric practiced unrealistic financial management, letting for example its depreciation reserve become insufficient, and consequently in the Showa depression which followed, the company found itself in a serious crisis.