Abstract: An object of the present invention is to provide a control method, for a wastewater purification system, where the status of a wastewater purification system employing a batch activated sludge process is accurately understood by analyzing the data waveforms of DO, ORP and pH. In the control method for a wastewater purification system, an aeration device is controlled by a programmable sequencer, a controller acquires respective data waveforms from a first sensor, a second sensor and a third sensor and the control status data of the programmable sequencer, the controller analyzes the data waveform of dissolved oxygen concentration from the first sensor, the data waveform of oxidation-reduction potential from the second sensor, and the data waveform of hydrogen ion concentration from the third sensor, and the controller performs an alarm process when a deviation from a previously fixed normal state is discovered as a result of the analysis.