Glucose degrading activity of gray low land paddy soil samples was measured anaerobically and aerobically by a mutarotase-glucose oxidase method after incubation under anaerobic and aerobic conditions. Cellulose degrading and protease activities were determined as well for comparison. Under anoxic conditions, the soil redox potential continuously decreased down to about −200mV, and the concentration of Fe（II）increased up to about 3.0mg g^<-1> dry soil at the end of the incubation, whereas the oxic conditions were maintained during the aerobic incubation. ATP contents of the anaerobic soil were almost half of the aerobic soil. In the soil incubated aerobically for 65 days, the glucose degrading activity was 0.37μmol g^<-1> dry soil h^<-1> when measured aerobically, that is three times higher than when measured anaerobically. In the soil incubated anaerobically, the activity measured anaerobically constantly increased to 0.88μmol g^<-1> dry soil h^<-1> during the same period, while ca.0.1μmol g^<-1> dry soil h^<-1> in the aerobic measurement. Cellulose degrading activity was also higher in the anoxic soil. In contrast, there was no significant difference in the protease activities between the oxic and anoxic soils.