This report examined the working properties and machine introduction conditions of the paddy iron-coated direct seeding cultivation system under conditions where the field scale and working systems were different. Two field scales; 1.5 ha and 0.3 ha, were compared by field size, and three working systems; a） included plowing, harrowing and leveling, b） excluding plowing, harrowing and leveling in direct seeding cultivation and c） the transplanting working system excluding plowing, harrowing and leveling. The operating costs of agricultural machines were calculated by measuring the effective field capacity and fuel consumption for each test plot. The effective field capacity of the whole process from soil preparation to harvesting was 2.3 ha h^–1 higher for the 1.5-ha field than for the 0.3-ha field, with the calorific value being 2241 MJ ha^–1 lower. With respect to working systems, the effective field capacity （calorific value） for the working system that included plowing, harrowing and leveling in 0.3-ha field was 0.8 ha h^–1 （3934 MJ ha^–1） higher than the working system that did not include these operations and 0.9 ha h^–1 （3722 MJ ha^–1） higher than the transplanting working system. The operating cost in the paddy direct-seeding work system in the 1.5-ha field was equivalent to the standard operation cost for conventional working systems in Shonai area. The operational cost, based on the findings if general-purpose tractors, plows, harrow, and rotary in 0.3 ha upland fields, for direct-seeding work systems and transplant work systems which exclude plowing, leveling, and leveling, can be below that of operation cost. Therefore, if plowing, harrowing, and leveling are included in the 0.3-ha field, these works should be conducted in the autumn season to increase feasible coverage.