The Japanese Diet is currently deliberating “the Bill for the Partial Amendment of the Civil Code of Japan.” In the Code, which is amended by the Bill, the concept of “impossibility” has a significant meaning. However, the meaning of “impossibility” in the Code is unclear because whether an obligation is impossible to perform or not is determined in light of the sources of obligation (such as contract), and the social standard or convention of trade practice. In other words, in the amended Civil Code, an obligation may be determined to be “impossible” to perform, even if the obligation is possible to perform in the physical sense. This article examines the meaning of “impossibility” in the amended Civil Code, based on the basic principles of interpretation.