PURPOSE: An anti-obesity composition using a Sargassum muticum extract is provided to be used as an anti-obesity composition, a hyperlipidemia treatment composition, and a fatty acid treatment composition and to manufacture foods or pharmaceutical products.CONSTITUTION: An anti-obesity composition contains a Sargassum muticum extract as an active ingredient. The extract is prepared using water, ethanol, or a mixture thereof. A hyperlipidemia treatment composition contains the extract as an active ingredient. A fatty liver treatment composition contains the extract as an active ingredient. A diet composition contains the extract as an active ingredient.COPYRIGHT KIPO 2013본 발명은 인슐린 등에 의해 분화 촉진된 지방전구세포의 지방세포로의 분화를 억제하고 고지방식이에 의한 비만 유도 마우스 모델에서 체중을 감소시키며 혈중 지질 농도를 낮추고 간의 지방 축적을 억제하는 활성을 경단구슬모자반 추출물을 이용한 항비만제 조성물을 개시한다.