A wastewater treatment method and a wastewater treatment apparatus securely and readily remove selenium, which is considered harmful, by removing not only 0-valent selenium, 4-valent selenium, and 6-valent selenium, but also -2-valent selenium. In the wastewater treatment method and the wastewater treatment apparatus for treating wastewater including selenium, -2-valent selenium included in the wastewater is oxidated by using an oxidant, or -2-valent selenium included in the water is removed by using a remover.