A plectrum sleeve has a sleeve body with an extending sheet. The sleeve body has a longitudinal open on an upper side thereof. The extending sheet is slantingly extending from an edge of a bottom side of the sleeve body. A plectrum piece is extending from an end of the extending sheet. The sleeve body is slid to a distal end of a finger with the extending sheet attached to the tip of the finger and the plectrum piece located in the front of the tip of the finger like an extension of the nail. The plectrum piece plunks a string of an instrument by bending or stretching the finger, the force back to the plectrum sleeve from the string will be strongly and steadily supported by the finger. A real and direct counterforce will be given to the finger and the user for better experience of plunking.