Disclosed is a mold assembly comprising: a cavity forming an inner space to be filled with resin containing metallic particles, and having a protruding part corresponding to a hole of a molded object; a first gate disposed at any one side of the cavity so as to inject the resin into the inner space; and a second gate disposed at another side of the cavity, and injecting the resin, which flows in a second direction intersecting with a first direction, into the inner space so as to change the arrangement of the metallic particles such that a weld line, formed according to the orientation of metallic particle in the first direction, is blurred in an area at which the flow of the resin is separated by the protruding part and then comes back together.