A box-shaped protective cover that covers an upper structural portion of a body of a vibrating compactor is manufactured by executing a cutting process for fashioning a single metal plate into a shape including a first planar portion, a second planar portion, an intermediate portion, and a plurality of side flaps, a bending process for bending or curving the side flaps and the intermediate portion, and a welding process for welding a side flap of the first planar portion to a side flap of the second planar portion.