Rice seeds sown directly in unwatered paddy fields are unreliable in their germination and young shoot emergence, though labour for cropping is much saved by such planting method. Effects of tillage operation on rice seed germination and shoot emergence out of soil were studied in unwatered paddy fields of Low-Humus Andosol soil (LHA) and Haplic Gray Lowland soil (HGL). Soil macropores holding moisture of more than -10 KPa of water potential were reduced by tillage operation in both soils, though pores corresponding to less than -10 KPa were not affected. After rain fall, tilled field more rapidly dried than untilled ones in both soils especially in LHA. Tillage operation lowered percentage of young shoot emergence in both LHA and HGL fields, and the percentage was higher in LHA field than HGL one regardless of the operation. Also stability of the emergence, which was evaluated based on coefficient of the variance, was reduced by tillage operation. Dominant part of no emergence seeds stopped their sprouting after beginning of root elongation, and percentage of such seeds in total seeds was over that of seeds normally emerging in the tilled HGL field. Only small part of total seeds was unable to emerge by stopping their growth after beginning of both root and shoot elongation, and such seeds were most often observed in tilled HGL field. In a laboratory experiment, beginning of shoot elongation of rice seeds was more delayed than that of root elongation by low soil moisture. Almost all rice seeds started their root elongation within 72 hr of seeding under soil moisture condition of more than -1 MPa, while initiation of shoot germination was repressed negatively corresponding to soil water potential at 72 hr.