Abstract: A fastening mechanism for a package device is provided, which includes a plurality of first protrusions stagger-arranged in two rows at an edge of a lid of the package device, wherein a gap is formed between the two rows of the first protrusions; a second protrusion formed on an edge of a body of the package device and corresponding in position to the gap; at least a projection formed on the edge of the body and substantially opposed in position to the second protrusion; and at least a recess formed on the edge of the lid and corresponding in position to the projection of the body. By coupling the lid to the body, the second protrusion is engaged with the gap between the first protrusions, and the projection of the body is engaged with the recess of the lid, so as to provide strong fastening effect for the package device.