The present invention provides a precursor for producing a tissue regenerating instrument that regenerates a tissue, including: a tube made of a biodegradable material provided with a lumen in a longitudinal direction a rod made of a biodegradable material swellable with a softening solvent, fixed to an inner wall of the tube substantially parallel to the longitudinal direction of the tube and an adhesive that fixes the rod to the inner wall of the tube, in which the rod in a non-swelled state has an occupied cross-sectional area perpendicular to the longitudinal direction that is smaller than a cross-sectional area of the lumen of the tube, and the occupied cross-sectional area perpendicular to the longitudinal direction of the rod in a saturated swelled state with the softening solvent is substantially the same as the cross-sectional area of the lumen of the tube.
