A method for forming an embedded circuit is disclosed. First, a substrate including a dielectric layer is provided. Second, the dielectric layer is entirely covered by a dummy layer. Then, the dummy layer is patterned and a trench is formed in the dielectric layer at the same time. Later, a seed layer is formed to entirely cover the dummy layer and the trench. Next, the dummy layer is removed and the seed layer covering the dummy layer is removed, too. Afterwards, a metal layer is filled in the trench to form an embedded circuit embedded in the dielectric layer.