An oxidation catalyst unit for a wet-type electrophotographic image forming apparatus which oxidizes a carrier vapor generated in a fusing unit and method for controlling the same are provided. The wet-type electrophotographic image forming apparatus includes a photoconductive medium, a laser scanning unit scans a laser beam onto the photoconductive medium, a developing unit develops a developer on the photoconductive medium, a transfer unit transfers the developer on the photoconductive medium to a recording medium, a fusing unit fixes the developer on the recording medium, and an oxidation catalyst unit oxidizes and resolves a carrier vapor generated in the fusing unit. The oxidation catalyst unit comprises a duct connected to the fusing unit to guide the carrier vapor generated in the fusing unit into the oxidation catalyst unit, a fan for guiding the carrier vapor into the duct, and a controller for varying a velocity of the fan according to data.