[Problem] A microorganism immobilized carrier is provided that is easy for microorganisms to adhere to, and is able to reduce the manufacturing cost of the microorganism immobilized carrier and the running cost of an apparatus that uses the microorganism immobilized carrier.
[Solution] A microorganism immobilized carrier is characterized by including a carbon component and a resin, having a zeta potential of from −25 mV to 0 mV, and containing microorganisms adhered to a surface thereof and/or an interior thereof. The microorganisms are preferably nitrifying bacteria. The carbon component preferably has a particle size of from 1 μm to 1000 μm.