A floated-type shielding mechanism including a cover, a shielding sheet, and a flexible conductor is provided. The cover is adapted to be fixed to a circuit board and covers a plurality of input/output (IO) ports of the circuit board. The shielding sheet is movably disposed at the cover and a back plate, and has a plurality of openings respectively corresponding to the IO ports. The flexible conductor deformably protrudes from an inner surface of the shielding sheet and is adapted to contact the IO ports. When the circuit board, the back plate, and the floated-type shielding mechanism are assembled into a case, the IO ports are exposed from a case opening and the flexible conductor is adapted to be deformed by pressing so that the shielding sheet presses against an inner wall surface around the case opening.