Abstract: A fuzzy controller is provided which enables even an unskilled operator to easily adjust various conditions in a glass pipe sealing process. The fuzzy controller has a fuzzy control processor including an image processing unit for processing and calculating image information as a softened state change value of the glass pipe and a combustion state value of burner flame, and a fuzzy control processing unit for calculating and outputting, by receiving a result of this calculation, a suitable control value for controlling parameters relating to the burner flame by fuzzy inference. The fuzzy controller may further has a fuzzy diagnosis support processor which, if there is an abnormality in the sealed portion of the glass pipe and if the state of the glass pipe after sealing is input to the manipulation instruction data input support processor by the operator, automatically ascertains the cause of the abnormality by using fuzzy inference and displays it on a CRT.