| AAA | Principal amount payment ability is the best |
| AA | Principal amount payment ability is very outstanding but inferior to AAA to some extent |
| A | Principal amount payment ability is outstanding, but a potential drop of efficiency exists in future principal amount |
| BBB | Principal amount payment ability is satisfactory, but a potential drop of efficiency exists in future principal amount payment ability depending on economic circumstances and aggravation of surrounding situations |
| BB | No current problem exists regarding principal amount payment, but potential speculative factors exist regarding future stability of repayment ability |
| B | Speculative outlook due to lack of principal amount payment ability and interest payment is uncertain in case of economic slump |
| CCC | Insecure state regarding currently insecure principal amount payment and very speculative outlook due to possibility of unfulfillment of obligatory debt repayment |
| CC | More insecure compared to superior grades |
| C | High possibility of unfulfillment of obligatory debt repayment and no ability of principal amount payment |
| D | Under situation of unfulfillment of obligatory debt repayment and bankruptcy |
