A packaging device and a manufacturing method thereof are provided. The packaging device includes an electronic unit, a conductive layer, a buffer layer, an insulation layer, and a first circuit structure. The electronic unit includes a pad. The conductive layer is disposed on the pad. The buffer layer is disposed on the conductive layer. The insulation layer surrounds the electronic unit and the buffer layer. The first circuit structure is electrically connected to the electronic unit. A part of the conductive layer is located between the electronic unit and the buffer layer, and an activity of the conductive layer is less than an activity of the pad.