A slim USB memory card is provided with retractable protection shield. A printed circuit board has a surface formed thereon a plurality of metal contacts. A main frame piece has two frame edges parallel with and opposite to each other for housing the printed circuit board. Each frame edge has an inner edge defined therein a track. A protection shield piece has two lateral sides. Each lateral side has a sliding bar, wherein the sliding bars sit on the tracks at the inner edges of the main frame piece, so as to glide back and forth on the tracks to perform cover and retract movement to protect the metal contacts.