To provide a biological deodorization apparatus which can keep the more excellent propagation and growth of a microbe than the conventional biological deodorization apparatus and can keep high efficiency of malodorous component decomposition for a long period of time.

This biological deodorization apparatus is constituted so that the malodorous component in the gas to be treated is decomposed biologically and removed by the microbe held by a carrier. A long-length carrier is used as the carrier which is obtained by mixing, entangling and joining a lot of a water-absorbable fiber, a lot of a hydrophobic stiff fiber and a lot of a hydrophobic fine fiber with one another so that the joined fibers are projected into the outside in the radial direction from the circumference of a core wire material. The joined fibers are preferably formed into loop-like shapes, particularly.