Since the end of World War II, and especially in the course of the latest several years a striking technological advancement has been realized in the iron and steel industry in Japan.<BR>In iron making the attainment of the increase of blast furnace volume, the improved quality of the major raw materials, i.e. coke, iron ore and limestone and the progress of beneficiation method have raised the iron making technique of this country up to the world level. For example, the maximum production of a blast furnace is 1,063 t/day/m³ and coke ratio 612 kg/ton pig. And as the result of repeated tests of oxygen-enriched blast, about 18% of increased production is expected to be brought about.<BR>In steel making the utilization of high purity oxygen remarkably enhanced the productivity of open hearths and arc furnaces without deteriorating the quality of steel, and it has at the same time enabled us to produce extremely low carbon steel, which has been considered hitherto hardly possible by the use of the usual ore smelting method. In the meantime the improvement of the quality of fire bricks and the advanced skill in furnace construction have served to increase the use of oxygen indirectly. The consumption of oxygen has increased in the recent 5 years to 15.7 m³/ton steel from 5.8 m³/ton steel, and fuel consumption has dropped to 730×10³ kcal/ton from 1,004 kcal/ton steel. The introduction of the L.D. type converter, however, has almost revolutionized the steel making methods. In view of the scarcity of scrap resources, in this country, this new method promises to prevail more and because of the superiority its products and the promoted productivity.<BR>As technological improvements in the field of slab-rolling and bar-rolling, the promotion of combustion control method brought about through the reform of soaking pits and reheating furnaces, and the increased capacity and speed in rolling may be pointed out. The fuel consumption has decreased to 150×10³-180×10³ kcal/ton ingot from 200×10³ kcal/ton ingot. The amplification of the dimensions of products by the improvement of rolling mills and the spread of the quality control must not be overlooked as an indication of technological improvements. The advancement in wire-rod rolling equipment is also very notable, by which better quality of products and high efficiency have been attained by means of the high speed continuous rolling method.<BR>In rolling heavy plates, operations far surpassing those heretofore in use in points of the quality, dimensions of the products and productivity is being carried out by using the four-high rolling stand newly equipped to the hithertoused mills. Particularly, the requirements for the carbon steel of improved quality and larger dimensions intended for huge vessels and the plates of high tensile steel (U.T.S.60, 70 and 80 kg/mm²) are getting severer, and the necessary equipments for their rolling, cooling and bettering have been gradually increased in number.<BR>In rolling strips, the strengthening of reheating capacity of hot rolling, the augmentation of rolling capacity by using slabs of larger size, the poroduction of high grade sheets by the improved cooling method have been achieved, and in the increase of rolling speed in cold rolling (1500 f.p.m.-4000 f.p.m.) and the exactness of product gauge by the reformed measuring method of steel plates, a remarkable stride has been made. By operating the continuous galvanizing line and electrolytic tinning line, no small contribution has been brought to the correlated industries in Japan.<BR>The technological advancement in the Japanese iron and steel making summarized above is nothing but the results of the already-published theories applied to as faithfully as possible, and embodied most economically in the actual operation, and further efforts are strongly desired to be made hereafter towards mo