The present invention relates to a metal polishing slurry containing abrasive grains, a metal-oxide-dissolving agent, and water, wherein the abrasive grains contain two or more abrasive grain species different from each other in average secondary particle diameter. Using the metal polishing slurry of the present invention, a metal polishing slurry can be obtained which gives a large polishing rate of an interlayer dielectric layer, and is high in the flatness of the polished surface. This metal polishing slurry can provide suitable method for a semiconductor device which is excellent in being made finer and thinner and in dimension precision and in electric characteristics, is high in reliability, and can attain a decrease in costs.