A package structure includes a semiconductor substrate, conductive pads, and conductive vias. The conductive pads are located on and electrically connected to the semiconductor substrate, and each have a testing region and a contact region comprising a core contact region and a buffer contact region, wherein along one direction, the conductive pads each have a maximum length less than a sum of a maximum length of the testing region and a maximum length of the buffer contact region. The conductive vias are respectively located on the core contact regions of the conductive pads.