Toward the goal of achieving carbon neutrality by 2050, technology development for the reduction of CO2 emissions is progressing in various fields. In the field of concrete, the development of technology to reduce CO2 emissions at each of the material stage, manufacturing stage, curing stage, and service stage is required. The authors conducted an experimental study to develop a technology to fix CO2 during concrete manufacturing. The newly developed technology was found to be able to fix about 10 kg of CO2 per 1 m3 of concrete. Further, the combined use of a two-stage mixing method, which divides the concrete mixing process into two separate steps, was found to produce concrete that, notwithstanding CO2 fixing by the above-mentioned method, exhibits no reduction in compressive strength nor loss of strong alkalinity, and thus is suitable for application to reinforced concrete structures.