Two representive processes of surface roughness formation in metal finishing, that is, roughness generation by tool-nose shape such as in cutting and smoothing process of surface roughness through selective solution or flow of surface asperities such as in electrolytic polishing, are studied. Components making up the surface roughness are examined by autocorrelation and spectrum analysis of the roughness records and the system diagram for roughness formation in these finishing processes is pictured. In cutting, the ideal roughness profile determined by tool-nose and tool feed is supplied as the in-put to the system, being transformed by swelling-up of work material during cutting, being added by the disturbances from the outside and forming the out-put roughness of the machined surface. The main sources of the roughness disturbances in cutting are the eccentric rotation of the machine-tool spindle and the vibration of the machine-tool and work. In smoothing process by electrolytic polishing, the surface roughness components of the shorter wave length are the more decreased. The transfer function for the surface roughness in the process is expressed as being nearly unity at very long wave length of roughness and as decreasing rapidly to zero with decreasig the wave length of roughness.