A puncture instrument includes a movable body movably disposed in a case, and a needle unit held by the movable body and having a needle. When a distal end face of the movable body is brought into abutment against a region to be punctured and the case is advanced toward the region to be punctured, the case is advanced together with the needle unit, and the tip end of the needle becomes protruded from the movable body and punctures the region to be punctured. An arm of the needle unit is abutted against and turned about a fulcrum member, thereby withdrawing the needle rearwardly.
