It would be ideal if bone substitutes could be absorbed by the human body upon the formation of new bone. Although calcium sulfate is absorbable, its biodegradation rate is very fast. Fortunately, this rate can be reduced significantly through various sintering techniques. This study demonstrates that the degradation rate of sintered CS specimens can be adjusted through the introduction of pores. Through various techniques, we introduced spherical pores with amounts ranging from 6.7 to 68 % into sintered CS specimens. The corresponding degradation rate in Hank's solution varied from 1.9 to 7.7 %/day and the cytotoxicity test results indicated low toxicity within the sintered CS specimens.