Disclosed are a highly safe treatment method for hyperlipidemia and a therapeutic agent for hyperlipidemia. Specifically, the invention provides a novel method for screening an agent for treating hyperlipidemia, more specifically, a method for screening a substance that can inhibit the production or function of gangliosides, particularly GM3, or inhibit the activity or expression of GM3 synthase to reduce a blood lipid level. A pharmaceutical composition, which can specifically inhibit the production of gangliosides, particularly GM3, thereby effective for hyperlipidemia treatment, and others are also provided.