A method for manufacturing a semiconductor package includes the following steps. A semiconductor process is performed to form an encapsulated semiconductor device, wherein the encapsulated semiconductor device comprises an encapsulating material and a semiconductor device encapsulated by the encapsulating material. A testing apparatus including a holder body, a positioning mechanism and a force applying bar is provided. The encapsulated semiconductor device is clamed by the holder body. A clamping position of the encapsulated semiconductor device is adjusted by the positioning mechanism. The positioning mechanism is removed. A predetermined force is applied to a part of the encapsulated semiconductor device exposed by the holder body by the force applying bar. If the encapsulated semiconductor device is failed by the predetermined force, a process parameter of the semiconductor process is modified to form a modified encapsulated semiconductor device.