A fixed seat for a tool has a sleeve joint pillar set into a polygonized pillar, of which the circumference side part contains abutment surfaces and edges. The abutment surface can abut the groove wall of the sleeve's square casing groove, and said edge or margin part permits spanwise locking of the sleeve during its rotation. A positioning convex part is protruded from an abutment surface on the circumference side part of the sleeve joint pillar, and interlocked with the positioning concave camber on the groove wall of the square casing groove. A lateral through-hole is set onto one side of the sleeve joint pillar. Both ends of the lateral through-hole pass through separately the abutment surface on the circumference side part of the sleeve joint pillar. A wall rim is formed between the abutment surface and the lateral through-hole, so that the positioning convex part could be squeezed flexibly.