PURPOSE: A sinker for an environment-friendly fishing tool and a manufacturing method thereof are provided to satisfy standard load by using modified high density sulfur. CONSTITUTION: A sinker for an environment-friendly fishing tool is as follows. The sinker is manufactured by mixing a mixture and modified sulfur. The mixture includes powder selected among metal, ceramic, and metal-ceramic composite. The modified sulfur is prepared by using a composition including sulfur and dicyclopentadiene as a starting material. The sinker is manufactured in order to have at least average specific gravity of 4g/cm^3.