Recently most of the Japanese tractors (10 - 40kw) have been equipped with an electro-hydraulic system for automatic depth and tilt control for the rotary tiller. This is a typical implement for the Japanese rice farming. The improved performance was needed to deal in the following areas. 1. In the muddy and rough soil pan condition, the tillage depth has to be kept at the satisfactory level while the engine speed stays within the operating range. 2. An automatic depth control must apply to rough tillage without using the conventional depth sensor (i.e. rotary tiller rear cover angle sensor). To meet these requirements, an automatic depth and tilt control system was developed. The two control modes (called MC-AUTO and E-AUTO) for the automatic depth control were developed by combining the conventional control method plus a load control method based on the fuzzy control theory. The automatic tilt control system was also incorporated in to the fuzzy control theory to eliminate what may have an adverse effect to the rotary tiller operation to extent that it affects crop production.The effectiveness of this system has been demonstrated by the field test data. The system improves the consistence of the hardpan profile, efficiency of tillage and also enables the ease of operation by eliminating human reaction time and errors.