An automatic tissue sampling apparatus for use with a biopsy needle set having an inner needle and an outer cannula is provided. An electronic impulse spectrum generator is connected to the electric heater, the permanent magnets reeled with windings and the magneto-electric poles of conductive rubbers. A mode selection input terminal receives a mode selection signal to select a first mode or a second mode of operation. The protruding portion protrudes towards at least one of the chassis and the lid member from an inner lateral surface of the reel unit guard. The screen first and second side opposing each other.