The present invention relates to a pharmaceutical composition and a health functional food composition for preventing, alleviating or treating inflammatory diseases, including Toxoplasma gondii GRA9 protein or a gene encoding the protein as an active ingredient. The present inventors have identified the C-terminal region essential for the NLRP3-mediated mechanism of action and function of Toxoplasma gondii GRA9 in macrophages, which are host immune cells and confirmed the substantial anti-inflammatory and antibacterial effects and the antiseptic effect in vivo. Accordingly, Toxoplasma gondii GRA9 protein or a gene encoding the protein is expected to be usefully utilized in the field of prevention or treatment of inflammatory diseases caused by an abnormal NLRP3-mediated inflammatory response, including sepsis.