A scrubber wastewater treatment method, according to one possible embodiment, includes obtaining a measurement of a turbidity or of a suspended substance concentration of scrubber wastewater and, upon determining that measurement of turbidity or suspended substance concentration is within a certain range, performing treatment. A scrubber wastewater treatment device, according to one possible embodiment, includes a magnetic powder adding device controllable to add a magnetic powder to be added to scrubber wastewater having been generated by treating combustion exhaust gas in a scrubber, and a controller configured to control an amount of the magnetic powder added by the magnetic powder adding device in accordance with a measurement value obtained by a sensor.
