Cloud-computing is in the limelight with expectation for cost reduction, because it alleviates the burden of initial investment and maintenance cost and based on pay-as-you-use billing policy. However, many suppliers of Cloud-computing service are suggesting diverse and complicated billing policies without consideration for setting reasonable service billing policy and definite criteria of properties to determine service billing system. So companies willing to use Cloud-computing service are hard to understand the billing system and often spend more expensive cost than necessary. Therefore, this study invested billing system properties of four representative suppliers. Based on these properties of billing system, this study found priorities using AHP survey which conducted to experts who are able to make decisions for adopting Cloud-computing in the company using or willing to use Cloud-computing service. We expect that this study can suggest basic guideline for comparing and analyzing properties of Cloud-computing service with standardized and objective method.