A device for retrieving calculus in a lumen of a living body includes an elongated member possessing an outer dimension configured to be positioned in the lumen of the living body, wherein the tubular body includes an inlet, an outlet and a retrieval space in the interior at a position between the inlet and the outlet. A foldable sealing member is positioned in the tubular body interior and is axially movable in distal and proximal directions, and a plunger is connected to the sealing member so that axial movement of the plunger axially moves the sealing member in the interior of the tubular body. The foldable sealing member is folded into a folded configuration when the plunger is axially moved in a distal direction toward the inlet and being spread out in a spread-out configuration when the plunger is axially moved in a proximal direction away from the inlet.
