JPH05240673

PURPOSE:To quickly and continuously diagnose a cultivating state in an on-line state by detecting current values about two or more kinds of items selected out of the temperature, pH, concentration of dissolved oxygen concentration, concentration of dissolved carbon dioxide, concentration of bacterium bodies, etc., of a culture liquid and performing analysis and calculation on the current values. CONSTITUTION:Current values about two or more kinds of items selected out of the temperature, pH, concentration of dissolved oxygen, concentration of carbon dioxide, and concentration of bacterium bodies of a culture liquid, concentration of carbon dioxide or oxygen in exhaust air from a culture tank, and amount of a defoaming agent fed to the culture tank are detected. Then relative deviations are calculated from the standard value of each item about two or more kinds of items selected out of the integrated amounts of the detected values and the integral amount of generated carbon dioxide found by calculation when one of the detected items is carbon dioxide. Thereafter, the degrees of normalness and abnormalness of a cultivating state are calculated from the relative deviation of each item by fuzzy reasoning and whether the cultivate state is normal or abnormal is judged by comparing the calculated normalness and abnormalness with their thresholds.