To provide a wastewater treatment method and a wastewater treatment apparatus, in which temporal variation of an organic matter concentration in a real wastewater is obtained, and a treatment condition of an organic matter in a real wastewater treatment tank can be examined appropriately.

In a wastewater treatment apparatus 1 that uses a wastewater treatment method by an activated sludge process that biologically processes organic wastewater, only a real wastewater supplied to a real wastewater treatment tank 12 when temporal variation of an organic matter concentration in a real wastewater is obtained, and an real sludge exhausted from the real wastewater treatment tank 12 in addition when a treatment state of an organic matter in the real wastewater treatment tank 12 is simulated are continuously or intermittently supplied to a miniature simulation tank 21 of a miniature simulation device, and then aeration is conducted. Thereafter, the concentration of carbon dioxide exhausted into the atmosphere along with organic matter decomposition reaction in the miniature simulation tank 21 is measured.