A medical safety needle is comprised of a needle body having a needlepoint and a side face a flexible sheath capable of fitting on the side face and so dimensioned as to hide the side face and a slider slidably fitting on the needle body and the sheath so as to be movable from a first position to expose the needlepoint to a second position to hide the needlepoint and so dimensioned as to rub on the sheath so as to fit the sheath onto the needle body when the slider moves from the first position to the second position.
