A method for producing an electronic part mounted substrate comprising an electronic part mounted on one side of a metal plate of aluminum or an aluminum alloy, the method comprising the steps of: plating the one side of the metal plate, having a surface roughness of 0.2 to 2.0 μm, with nickel or a nickel alloy to form a plating film of nickel or the nickel alloy directly on the one side of the metal plate, the plating film being plated to have a thickness of 0.1 to 10 μm; applying a silver paste on the plating film, the silver paste being a bonding agent wherein fine silver particles having an average primary particle diameter of 1 to 200 nm coated with an organic compound having 8 or less of carbon atoms are dispersed in a dispersing medium; arranging the electronic part on the silver paste applied on the plating film, the electronic part having a surface to be bonded to the plating film, the surface being covered with a metal capable of being bonded with the silver paste, said metal being in contact with the silver paste; and sintering silver in the silver paste to form a silver bonding layer containing a sintered body of silver to bond the electronic part to the plating film with the silver bonding layer, characterized in that: the method further comprises a step of surface-machining the one side of the metal plate so as to cause the surface roughness thereof to be 0.2 to 2.0 μm before the plating film is formed on the surface-machined surface of the metal plate, the plating of the one side of the metal plate causes the plating film to have a surface roughness of 0.4 to 2.0 μm, the silver paste is applied directly on the plating film with the surface roughness of 0.4 to 2.0 μm, and the surface roughness of each of the surface-machined metal plate and the plating film is an arithmetic surface roughness Ra calculated on the basis of JIS B0601. plating the one side of the metal plate, having a surface roughness of 0.2 to 2.0 μm, with nickel or a nickel alloy to form a plating film of nickel or the nickel alloy directly on the one side of the metal plate, the plating film being plated to have a thickness of 0.1 to 10 μm; applying a silver paste on the plating film, the silver paste being a bonding agent wherein fine silver particles having an average primary particle diameter of 1 to 200 nm coated with an organic compound having 8 or less of carbon atoms are dispersed in a dispersing medium; arranging the electronic part on the silver paste applied on the plating film, the electronic part having a surface to be bonded to the plating film, the surface being covered with a metal capable of being bonded with the silver paste, said metal being in contact with the silver paste; and sintering silver in the silver paste to form a silver bonding layer containing a sintered body of silver to bond the electronic part to the plating film with the silver bonding layer, characterized in that: the method further comprises a step of surface-machining the one side of the metal plate so as to cause the surface roughness thereof to be 0.2 to 2.0 μm before the plating film is formed on the surface-machined surface of the metal plate, the plating of the one side of the metal plate causes the plating film to have a surface roughness of 0.4 to 2.0 μm, the silver paste is applied directly on the plating film with the surface roughness of 0.4 to 2.0 μm, and the surface roughness of each of the surface-machined metal plate and the plating film is an arithmetic surface roughness Ra calculated on the basis of JIS B0601. the method further comprises a step of surface-machining the one side of the metal plate so as to cause the surface roughness thereof to be 0.2 to 2.0 μm before the plating film is formed on the surface-machined surface of the metal plate, the plating of the one side of the metal plate causes the plating film to have a surface roughness of 0.4 to 2.0 μm, the silver paste is applied directly on the plating film with the surface roughness of 0.4 to 2.0 μm, and the surface roughness of each of the surface-machined metal plate and the plating film is an arithmetic surface roughness Ra calculated on the basis of JIS B0601.