An image sensor package and a manufacturing method thereof are provided. The image sensor package includes a redistribution circuit structure; an image sensing chip disposed on the redistribution circuit structure and having a sensing surface, on which a sensing area and a first conductive pillar arranged in the periphery of the sensing area are disposed; a lid covering the sensing area; an encapsulant disposed on the redistribution circuit structure and encapsulating at least part of the image sensing chip and the cover; and a top tier semiconductor chip disposed above the image sensing chip and having an active surface on which a first conductor is disposed. The first conductor overlaps the image sensing chip in a direction perpendicular to the sensing surface. The first conductive pillar and the first conductor are aligned and bonded to each other to electrically connect the image sensing chip and the top tier semiconductor chip.