The present invention provides a nucleus pulposus filler or the like which istobe packed into an area in deformed intervertebral disc wherein normal nucleusshouldbe located and can be stabley maintained for a long time. More preferably, thepresentinvention provides a nucleus pulposus filler comprising a crosslinkedchondroitinsulfate as an active ingredient. The photocrosslinked chondroitin sulfate ispreferablythe following one: a photocrosslinked chondroitin sulfate obtainable byfreezing aphotoreactive chondroitin sulfate-containing solution comprising: aphotoreactivechondroitin sulfate to which a photoreactive group is bound； an aqueoussolvent capableof dissolving the photoreactive chondroitin sulfate； and any one substanceselected fromthe group consisting of an alcohol having aqueous solvent miscibility, asurfactant, anda cheleting agent； irradiating the resulting frozen product with light； andthen meltingthe frozen product. The filler can be provided as a kit by packing it into acontainerfrom which the filler can be pushed out.
