The present invention provides a monoclonal antibody displaying excellent specificity against heparan sulfate saccharide chains for the analysis of heparan sulfate saccharide chains specific to dentin. The invention also provides a method of evaluating reproductive dentin using the monoclonal antibody. The anti-heparan sulfate monoclonal antibody reacts against dentin-derived heparan sulfate and in particular the anti-heparan sulfate monoclonal antibody reacts strongly and specifically with uncalcified predentin regions. In the method of evaluating dentin, the antibody is reacted against an isolated dentin-derived sample and the reaction is used in order to evaluate the development of dentin.