Fed-batch culture was carried out to increase cell mass followed by batch culture for spore production of Bacillus thuringiensis. High cell mass obtained by increasing the feeding glucose concentration in constant fed-batch culture did not proceed to spore formation. However, intermittent fed-batch culture which supported fast cell growth resulted in good sporulation during subsequent batch culture, and the maximum cell mass of 72.6 g/L and spore concentration of 1.25 x 10(10) spores/mL could be obtained.