A calculus retrieving device for retrieving calculus in a renal pelvis , the calculus retrieving device comprising: an elongated member sized to be positioned in an ureteral lumen of an ureter and movable toward the renal pelvis , the elongated member including a lumen opening at a distal end of the elongated member , ;the elongated member possessing an inner surface; a tubular member movably positioned inside the elongated member and possessing an outer surface, the tubular member possessing a distal-most end, the tubular member including a lumen opening at a discharge nozzle located at a distal end of the tubular member ; a space between the inner surface of the elongated member and the outer surface of the tubular member ; characterized in that the space between the inner surface of the elongated member and the outer surface of the tubular member receives a first fluid; an expandable and contractable renal cover part is fixed to the elongated member and positionable in the renal pelvis , the renal cover part including an interior communicating with the space so that the first fluid flows into the interior of the renal cover part when the renal cover part is positioned in the renal pelvis to expand the renal cover part from a contracted state to an expanded state in which the renal cover part covers one part of the renal pelvis while an other part of the renal pelvis containing the calculus is not covered by the renal cover part ; the lumen in the tubular member is configured to receive a second fluid that is then discharged from the lumen in the tubular member by way of the discharge nozzle and is introduced into the other part of the renal pelvis to move the calculus located in the other part of the renal pelvis . an elongated member sized to be positioned in an ureteral lumen of an ureter and movable toward the renal pelvis , the elongated member including a lumen opening at a distal end of the elongated member , ;the elongated member possessing an inner surface; a tubular member movably positioned inside the elongated member and possessing an outer surface, the tubular member possessing a distal-most end, the tubular member including a lumen opening at a discharge nozzle located at a distal end of the tubular member ; a space between the inner surface of the elongated member and the outer surface of the tubular member ; characterized in that the space between the inner surface of the elongated member and the outer surface of the tubular member receives a first fluid; an expandable and contractable renal cover part is fixed to the elongated member and positionable in the renal pelvis , the renal cover part including an interior communicating with the space so that the first fluid flows into the interior of the renal cover part when the renal cover part is positioned in the renal pelvis to expand the renal cover part from a contracted state to an expanded state in which the renal cover part covers one part of the renal pelvis while an other part of the renal pelvis containing the calculus is not covered by the renal cover part ; the lumen in the tubular member is configured to receive a second fluid that is then discharged from the lumen in the tubular member by way of the discharge nozzle and is introduced into the other part of the renal pelvis to move the calculus located in the other part of the renal pelvis . <EOS>