Disclosed herein is a medical instrument used for harvesting biological tissues of a predetermined biological organ and a medical system. The medical instrument includes: a main body portion that has an elongated shape and has a distal part having a helical groove formed in an outer surface, a fluid lumen through which fluid is allowed to flow and pass, and a through-hole communicating with the fluid lumen and the outer surface of the distal part, at least part of the distal part being stuck into the biological organ； and a tubular member that has an insertion lumen into which the main body portion is inserted movably in axial direction and forms a gap through which fluid is allowed to flow and pass between the main body portion and the tubular member in a state in which the main body portion is inserted in the insertion lumen. The medical system includes: the medical instrument； a fluid supply unit that supplies a fluid into the fluid lumen of the main body portion； and a fluid drawing unit that draws the fluid existing in the gap.
