The present invention relates to a bioreactor for sewage and wastewater treatment, which is capable of agitating and supplying oxygen simultaneously. A bioreactor of the present invention, comprises a culture drum in which microorganisms are cultured; a supplier for supplying a culture solution, and organic and inorganic media to the culture drum, the supplier including a supply tube connected to an upper side of the culture drum, and a pump connected to the supply tube for supplying the culture solution to the culture drum; an agitator for agitating the culture solution by spraying air into the culture solution in the culture drum, the air being supplied from an air blower; and a thermostatic controller for controlling a temperature of the culture solution and disinfecting the interior of the culture drum.