The ISO 11138 series on biological indicator (BI) are insufficient for the concrete description on suspension, carrier and recovery culture medium of microorganisms for preparation of BI. Suspension, carrier and culture medium have a potential to affect D value of BI. Individual effect of suspension, carrier or culture medium on D value of BI was reported, but the combination effect of these factors on D value was not reported yet and the author did not confirm individual effect on D value contrary to the previous papers. The combination effect of salt from suspension when drying and pore of the carrier for entrapping microorgamisms will be speculated to prevent sterilization. D value differed depending on constitute of culture medium, so it will be required to confirm if the constitute of soybean casein digest broth in WD 14161 is appropriate or not to attain the exact D value.