In this paper, author presents the production and cost computation which are said to be the main point in the design of earthmoving works executing by bulldozer. Theoretical consideration on design has been executed in order to make clear the every problem, especially those hitherto no clear and unknown, and by putting the records on earthmoving works in order, it was successful to obtain several factors and coefficients which are neccessary for the computations, consequently those computations have been led up to the level of practical use.To caluculate the quantity of earth work, author introduced a practical formula, in which a field-work coefficient is used, and this propose formula, makes the calculation of the quantity of earth work much simpler than the conventional method. Moreover, if the field-work coefficients, which the author has obtained by classifying the degree of easiness of work according to the kind of work, are used, the discrepancy between the estimated work efficiency and the actual work efficiency can be minimized. This is the important point of the present study.In computing the work cost, a concrete calculation of various costs such as repair cost, residual value, depreciation cost, etc. has been made possible by extending the theory of depreciation which states that the sum of the depreciation and repair costs is constant, to the conditions of various kinds. The problems regarding the method of computation of the rental which is subject to the fluctation of commodity prices, or the administration expenses, have been also solved.Further, the author obtained, through actual experiment, various coefficients neccessary for computing the rentals and especially the economical life of various types of bulldozer and the ratio of the maintenance and repair expenses to the purchasing expenses, and made it possible to calculate the practical value such as the rental for the bulldozers which are now in use in Japan. In addition, the author has shown a few examples of computation.On estimation of repair costs, author established a method of calculating repair costs, taking into consideration the time and number of the periodical overhauls of machine, and succeed in obtaining on correct estimation of the repair expenses, because he was able to for each type.Regarding the calculation of operating costs, the author collected and classified many deta concerning the per hour consumption of the main fuel and lubricant oils, and was able to fine out the increase and decrease of consumption, which vary with the change of the work condition. At the end of this paper, the author added tables and graphs with hourly quantity of earth work and unit costs by the type of bulldozer, according as the easiness of the work and carrying distances.