PROBLEM TO BE SOLVED: To provide a technique for allowing to effectively reduce an odor derived from a lower alkyl (meth) acrylate in a dental hardening composition containing the lower alkyl (meth) acrylate.SOLUTION: A dental hardening composition contains a lower alkyl (meth) acrylate and a specific lactone aromatic. Preferably, the dental hardening composition contains 0.005-5 mass% of the lactone aromatic. The odor of the lower alkyl (meth) acrylate can be reduced by combining the lactone aromatic.