NOVELTY - Cathode electrolysis of ferrite-type stainless steel plate is carried out in aqueous solution having pH of 11 or more, and a passive film is formed on an outermost surface. The thickness of film is set to 4 nm or less. The surface of plate is made to produce a pit by immersing plate in aqueous solution of ferric chloride and hydrochloric acid. The ratio of projected area of pit generation portion occupied on surface is made into 40% or more, and average surface roughness on the surface of steel plate is made into 0.05-0.3 mu m. Thus, fine-roughened stainless steel plate is manufactured.    USE - Manufacture of fine-roughened stainless steel plate used as substrate for manufacturing thin film silicon solar cell (claimed).    ADVANTAGE - The fine-roughened stainless steel plate is efficiently manufactured with improved corrosion resistance. The thin film solar cell formed using the steel plate has high photoelectric conversion efficiency.    DETAILED DESCRIPTION - Cathode electrolysis of ferrite-type stainless steel plate is carried out at electric potential of -0.5 to -2.2 V (vs.SCE) in aqueous solution having pH of 11 or more, and a passive film is formed on an outermost surface. The steel plate consists of (in %mass) carbon (0.0001-0.15), silicon (0.001-1.2), manganese (0.001-2), phosphorus (0.001-0.05), sulfur (0.0005-0.03), nickel (0-2), copper (0-1), chromium (11-32), molybdenum (0-3), aluminum (0-1), niobium (0-1), titanium (0-1), nitrogen (0-0.0025), boron (0-0.01), vanadium (0-0.5), tungsten (0-0.3), and calcium, magnesium, yttrium and rare earth element (0-0.1 in total), and remaining iron and unavoidable impurities. The thickness of passive film is set to 4 nm or less based on silicon dioxide conversion depth of 1/2 of oxygen-concentration position in element profile from outermost surface by auger electron spectroscopy (AES) to depth direction. The surface of plate is made to produce a pit by immersing cathode electrolyzed steel plate in aqueous solution obtained by mixing ferric chloride (2-50) and hydrochloric acid (0.1-20). The ratio (pit occupied area rate) of projected area of pit generation portion occupied on the surface is made into 40% or more, and average surface roughness on the surface of steel plate is made into 0.05-0.3 mu m by etching process. An INDEPENDENT CLAIM is included for manufacture of thin film silicon solar cell.