The present invention provides: a method for manufacturing a metallized substrate by which a fine pattern can be formed more easily; a metallized substrate manufactured by the method; and a metal paste composition to be used in the method. The metallized substrate has: a sintered nitride ceramic substrate (10); a titanium nitride layer (20) on the sintered substrate (10); an adhesion layer (30) on the titanium nitride layer (20); and a copper plating layer (40) on or above the adhesion layer (30), wherein the adhesion layer (30) contains copper and titanium, and has a thickness of no less than 0.1 μm and no more than 5 μm.