A manufacturing method of an interposed substrate is provided. A photoresist layer is formed on a metal carrier. The photoresist layer has plural of openings exposing a portion of the metal carrier. Plural of metal passivation pads and plural of conductive pillars are formed in the openings. The metal passivation pads cover a portion of the metal carrier exposed by openings. The conductive pillars are respectively stacked on the metal passivation pads. The photoresist layer is removed to expose another portion of the metal carrier. An insulating material layer is formed on the metal cattier. The insulating material layer covers the another portion of the metal carrier and encapsulates the conductive pillars and the metal passivation pads. An upper surface of the insulating material layer and a top surface of each conductive pillar are coplanar. The metal carrier is removed to expose a lower surface of the insulating material layer.