Bioprocesses have been operated according to the judgment of experts who are skilled operators and have long experience. In almost all cases, these experiences are described by linguistic IF-THEN rules. Fussy inference is one of the powerful tools to incorporate linguistic rules into computational algorithms for application to process control. Fuzzy control is categorized into two types: the direct fuzzy control of process variables such as sugar feed rate in fed-batch culture and broth temperature in batch operation, and the indirect control of bioprocesses in which the phase recognition Is first done by fuzzy inference using process variables such as DO, sugar concentration, pH and so on and then the control strategies having been constructed in each phase are used for the process operation. Fuzzy control has already been applied to practical industrial processes, such as production of a pravastatin precursor and vitamin BE, and the Japanese sake mashing process. In this review, these industrial practices of fuzzy control are introduced.