The present invention provides a nucleus pulposus filler or the like which is to be packed into an area in deformed intervertebral disc wherein normal nucleus should be located and can be stabley maintained for a long time. More preferably, the present invention provides a nucleus pulposus filler comprising a crosslinked chondroitin sulfate as an active ingredient. The photocrosslinked chondroitin sulfate is preferably the following one: a photocrosslinked chondroitin sulfate obtainable by freezing a photoreactive chondroitin sulfate-containing solution comprising: a photoreactive chondroitin sulfate to which a photoreactive group is bound； an aqueous solvent capable of dissolving the photoreactive chondroitin sulfate； and any one substance selected from the group consisting of an alcohol having aqueous solvent miscibility, a surfactant, and a cheleting agent； irradiating the resulting frozen product with light； and then melting the frozen product. The filler can be provided as a kit by packing it into a container from which the filler can be pushed out.
