This study proposes a history unit plan aimed at the reconstruction of historical significance of junior high school students. In some cases, historically significant items are boldfaced in textbooks by junior high school students. However, as citizens, it is not enough to judge whether or not historical significance is important in a textbook. Therefore, in this study, The Historical Thinking Project (Canada) and The Critical Thinking Consortium’s unit plan were used as a basis for the development and practice of a history unit. This unit aims to reconstruct “historical significance” by 1) understanding the diversity of criteria of “historical significance,” 2) progressing “historical significance,” and 3) reconstructing “historical significance” from a broader perspective. In particular, the textbook’s boldface type was used as a material for the performance task, “Let’s submit an opinion about the boldface type to the textbook writer”, in order to reconstruct historical significance. The outcome of this research hints at future possibilities of bigger reforms in the history curriculum.