A manufacturing method of a metal structure is disclosed, which includes the following steps: forming a seed layer on a substrate; forming a patterned metal layer on the seed layer, wherein the patterned metal layer includes a metal member; forming a first patterned photoresist layer on the seed layer, wherein a thickness of the first patterned photoresist layer is less than a thickness of the patterned metal layer; and performing a first patterning process to the seed layer through the first patterned photoresist layer to form a patterned seed layer, wherein after the first patterning process, the metal member includes a first part and a second part, the first part is disposed between the patterned seed layer and the second part, and a width of the first part is greater than a width of the second part.