With an objective of establishing a mechanization system suitable for direct seeding if rice under wet field conditions in the Muda area, some machinery tests were undertaken during the period of 1988 to 1990. Tillage and puddling operations with tractors under wet soil conditions showed a working rate of 0.5-0.7 ha/hr. The pudding operations with a wide rotary tiller considerably raised field work efficiency. Surface water drainage through the ditches opened by an auger trencher reduced incidences of vacant spots to the level of 4.4%, which was comparable to 9.3% under the ordinary method. Working rate of that trencher was estimated at approximately 0.7-0.8 ha/hr. A prototype of drill seeder was developed to explore the feasibility of a drilling method for direct seeding of rice under wet conditions. The stand establishment with a row space of 30 cm was inferior to that with broadcasting, but coefficient of variation (CV) values were improved. Drilling operation was accomplished as a working rate of 0.8 ha/hr.