The present disclosure relates to a technique capable of being used even in an environment that needs to be maintained at a low temperature. The present disclosure may include a fan configured to generate a flow of air, an absorbing material disposed downstream from the fan and configured to absorb a malodorous substance from air passing therethrough and to desorb the malodorous substance by being heated, an upstream heater disposed downstream from the fan and upstream from the absorbing material and configured to heat air entered the absorbing material, a catalyst configured to decompose the malodorous substance desorbed from the absorbing material, and a cooler configured to cool air passed through the catalyst.