To provide a replacement method of a cutter of an apparatus for manufacturing solid fuel from refuse, and a tool using for it, easily attaching and detaching a cutter piece without taking much time and trouble, and also replacing a fixed cutter in a short time.

In this replacement method of the cutter of the apparatus 10 for manufacturing granular solid fuel, the heated and compressed refuse 12 is pushed into a forming passage 13 of the fixed cutter 14 by the movable cutter 25b. The ring-like fixed cutter 14 is composed of a number of cutter pieces 18 disposed radially and forming the forming passage 13 radially, and the movable cutter 25b is provided inside the fixed cutter 14 to make a pair with the fixed cutter 14. Metal fittings 24 for fixing the front sides of the respective cutter pieces 18 disposed like a ring are detached, and instead of the metal fittings 24, and the tool 30 having a fixed ring part 33 is attached to the respective cutter pieces 18 disposed like a ring by a fixing bolt to replace the fixed cutter 14.