Disclosed are: a copper metal film which has good adhesion to a substrate, low volume resistivity, and good deep-part metal properties; and a method for producing a copper metal film, wherein the copper metal film can be produced by reducing a substrate to a deep part thereof without damaging the substrate. Specifically disclosed is a copper metal film obtained by treating a copper-based particle deposition layer containing both copper oxides and a metallic transition metal or alloy, or a transition metal complex containing a metal element, with gaseous formic acid and/or formaldehyde heated to 120° C. or higher. The copper oxide is preferably copper (I) oxide and/or copper (II) oxide. The transition metal, alloy or metal complex are preferably a metal selected from the group consisting of Cu, Pd, Pt, Ni, Ag, Au and Rh, an alloy containing the metal, or a complex containing the metal element, respectively.