PURPOSE: To provide the process controller which enables switching without fluctuating an output signal from a manual operation when any fault is generated at a controller.

CONSTITUTION: A process controller 3 is provided with a computer 5 for inputting a state signal 4 of a process from a plant 1 and outputting a control output 8 corresponding to the differentiated value of a driving output 9 by executing velocity type control operation to deviation from a command value 6 of the process and an integrating means 15 for outputting a manual increase/-decrease signal 16 to be outputted corresponding to the control output 8 through an integrating element as the driving output 9 with the manual operation when no desired signal is outputted from the computer 5.