A catalyst-aided chemical processing method is a novel processing method having a high processing efficiency and suited for processing in a space wavelength range of not less than several tens of .mu.m. The catalyst-aided chemical processing method comprises: immersing a workpiece in a processing solution in which a halogen-containing molecule is dissolved, said workpiece normally being insoluble in said processing solution; and bringing a platinum, gold or ceramic solid catalyst close to or into contact with a processing surface of the workpiece, thereby processing the workpiece through dissolution in the processing solution of a halogenide produced by chemical reaction between a halogen radical generated at the surface of the catalyst and a surface atom of the workpiece.