The present invention aims to provide a corneal endothelium cell proliferation accelerator and a therapeutic agent for a disease relating to corneal endothelium damage, which are administered into the anterior chamber. bFGF is released in a sustained manner by forming bFGF sustained-release gelatin hydrogel particles wherein bFGF is carried on gelatin hydrogel. Therefore, the proliferation of corneal endothelium cells can be accelerated persistently by administration of a preparation containing the bFGF sustained-release gelatin hydrogel particles into the anterior chamber, and diseases relating to corneal endothelium damage can be treated.