Nucleosomes are extremely stable histone–DNA complexes that form the building blocks of chromatin, which accommodates genomic DNA within the nucleus. The dynamic properties of chromatin play essential roles in regulating genomic DNA functions, such as DNA replication, recombination, repair, and transcription. Histones are the protein components of nucleosomes, and their diverse modifications and variants increase the versatility of nucleosome structures and their dynamics in chromatin. Therefore, a technique to evaluate the physical properties of nucleosomes would facilitate functional studies of the various nucleosomes. In this report, we describe a convenient assay for evaluating the thermal stability of nucleosomes in vitro.