Repeated itaconic acid production using an air-lift bioreactor was carried out by three methods-two with cell recycling by means of centrifugation and filtration by a stainless steel filter set inside the bioreactor and one by repeated batch culture without cell recycling. In a flask culture, repeated itaconic acid production was stable for 9 cycles (45 d) and the production rate was 0.47 g/l/h. However, in the air-lift bioreactor, it was difficult to produce itaconic acid in the repeated batch culture with cell recycling for a long period due to a decrease in fluidity resulting from an increase in mycelium concentration. In the method without cell recycling, however, repeated itaconic acid production was stable for 4 cycles (21 d) and the production rate was 0.37 g/l/h.