Blast furnace slag cement has been extensively utilized in Japan not only in mass concrete structures but also in general civil infrastructure, due to its advantages in promoting the effective utilization of industrial byproducts and reducing CO₂ emissions. However, structures constructed with blast furnace slag cement concrete have reported a higher incidence of cracking compared to those constructed with ordinary Portland cement. These cracks are typically attributed to the significant autogenous shrinkage, low tensile creep, and reduced tensile strength associated with Blast furnace slag cement. Nevertheless, the dominant mechanism underlying these phenomena has not been clearly identified. The authors have previously demonstrated that the addition of gypsum and limestone powder has the potential to suppress drying shrinkage in blast furnace slag cement mortar under high-temperature curing histories experienced during early ages. In this study, the drying shrinkage of blast furnace slag cement mortar with added gypsum and limestone powder was evaluated under high-temperature histories simulating those found in massive concrete and the optimal amounts of these additives for reducing shrinkage were identified. Subsequently, the autogenous shrinkage of blast furnace slag cement concrete incorporating these optimal dosages of gypsum and limestone powder was measured. The results revealed that the optimal addition of gypsum and limestone powder successfully suppressed the autogenous shrinkage of the concrete by 20–30%. Furthermore, when shrinkage-reducing agent was incorporated, it was reduced by about 40%.