Provided are a freshness-preserving agent obtained by a simple method and exhibiting excellent adsorptivity and antibacterial properties, a gas purification device composed of the freshness-retaining agent, and a gas purification system. The freshness-preserving agent is made by adhering tea catechin to the surface and / or inside of the charcoal powder and adhering between the charcoal powder by interposing clay between the charcoal powder, and has excellent adsorbability and antibacterial properties. Play.簡便な方法により得られ、優れた吸着性及び抗菌性を奏する鮮度保持剤、当該鮮度保持剤から構成される気体浄化装置、及び気体浄化システムを提供する。鮮度保持剤は、炭粉末の表面及び／又は内部に茶カテキンを付着させると共に、前記炭粉末間に粘土類を介在させて前記炭粉末間を付着して成り、優れた吸着性及び抗菌性を奏する。
