PURPOSE: To provide an apparatus for removing an acetic acid odor with microorganisms effectively in a stable condition.

CONSTITUTION: A microorganism deodorization tank 13 is installed which has a sprinkler 11 and a carrier 14 in which a microorganism membrane is formed with the addition of active sludge. A concentration meter 16 for detecting the concentration of acetic acid in a gas to be deodorized which is introduced to the tank 13 and an acetic acid gas tank 18 are installed. Acetic acid is led to the deodorization tank 13 from the acetic acid gas tank 18 corresponding to the concentration of acetic acid detected by the concentration meter 16 to keep the load in the tank 13 almost constant so that the deodorization tank 13 is operated stably.