The reduction of CO2 emission from various productions and service processes has been already recognized to be not enough, CO2 sequestration is necessary for decreasing the concentration of CO2 in the atmosphere. In this study, the author proposed a new method for sequestrating CO2, which encloses CO2 bubbles into foamed concrete, and then investigated the strength, water absorption, drying shrinkage, alkalinity, CO2 uptake caused by the carbonation, and micro-structure, etc. of CO2 -foamed concrete (CFC) and Air-foamed concrete (AFC) using different kinds of cement. The experimental results show that (1) Mixing CO2 bubbles into concrete didn't harm 28-days compressive strength and flexural strength in case of using ordinary Portland cement, and didn't increase drying shrinkage of foamed concrete. (2) The pH of CFC with 3 months age was kept to be more than 12.0, when CO2 content was below 60% by volume, (3) Internal CO2 bubbles yielded a little increase of CaCO3, and (4) CO2 sequestration in CFC was mainly structural trapping rather than carbonation.