Refractory brick is a brick which has a high-temperature strength property. It is therefore, used in the construction of furnaces and equipments in industries having a manufacturing processes which require high temperatures such as cement, steel, ceramics, etc. These industries are fundamental of national development. In the past, Thailand had to import a large amount of refractory bricks. But nowadays, the production of refractory bricks are large enough for local consumptions and exports. However, the market share is still small because of the competition with Japan, England and West Germany. Moreover, the cost of production is also higher than those of the competitors. An appropriate cost accounting system will be useful for cost control and decision making. It will result in more efficiency in the production of refractory bricks so that they can compete with those other countries. Refractory bricks can be produced in different sizes and shapes which are of international standard. Moreover, they can be made to any specification required by many and widely diversified industrial application, thus, refractory bricks are different from type to type and formula to formula. The study of cost accounting system of refractory brick industry consists of interviewing staffs involving in accounting and production functions and observing the procedures of the existing system. The proposed system resumes the appropriate part of the existing system but some procedures are added, especially, the designing of forms to facilitate the collection of data and report preparation. The cost accounting system which is appropriate to the characteristics of refractory brick industry is operation costing system which is the hybrid of job cost and process cost system. From the study of cost accounting of this industry, the author would recommend that businesses in refractory brick industry control actual cost by using estimate cost. That is, they have to prepare in adva the estimation of material, direct labor and manufacturing overhead cost for the production of each formula. The comparisons are made between actual and estimate costs and investigations of variances are then performed. Applying the suggested system, it is able to properly collect data for each product and effectively control cost.