A gas sprayer mounted on an edge removing robotic arm is disclosed, wherein the edge removing robotic arm circles around along the edges of a substrate and sprays a chemical solvent over the edge surface of the substrate to dissolve photoresist materials attached to the edges of the substrate; the edge removing robotic arm has a pumping conduit for sucking out the chemical solvent sprayed over the surface of the substrate and dissolved photoresist particles; the gas sprayer is mounted on the top of the edge removing robotic arm and comprises a hooked nozzle extending forward around the front end of the edge removing robotic arm and facing an opening of the pumping conduit to spray gas out so as to prevent the chemical solvent sprayed out from the edge removing robotic arm from splashing onto the interior of the substrate.