A semiconductor producing apparatus is capable of quickly and accurately changing a controlled variable to a target value to thereby make the controlled variable quickly follow the target value. Moreover, the controlled variable and target value can be adjusted automatically, thus improving the productivity of a process. The semiconductor producing apparatus includes a PID adjustment section to which a target value and a detected control value are inputted through an adder, a pattern generation section having an approximate function for calculating a pattern output and making it possible to change the pattern output in accordance wit parameter values of the approximate function, and a switcher for switching between an output including at least an output of the pattern generation section and an output of the PID adjustment section to thereby generate an output.