A semiconductor package structure including a sensor die, a substrate, a light blocking layer, a circuit layer, a dam structure and an underfill is provided. The sensor die has a sensing surface. The sensing surface includes an image sensing area and a plurality of conductive bumps. The substrate is disposed on the sensing surface. The light blocking layer is located between the substrate and the sensor die. The circuit layer is disposed on the light blocking layer. The sensor die is electrically connected to the circuit layer by the conductive bumps. The dam structure is disposed on the substrate and surrounds the image sensing area. Opposite ends of the dam structure directly contact the sensor die and the light blocking layer. The underfill is disposed between the dam structure and the conductive bumps.