The author begins by alluding to indigenous, unofficial laws functioning in Japanese society, that is, functioning as a supplement to, a counter to, a modification of, or even a means of undermining, the official state law. Next, such specific unofficial jural postulates as family idea, hamlet spirit, common kin principle, status order, Tenno adoration, and god conception are identified as means of justifying the ideas and values of indigenous, unofficial laws. A diffuse, unofficial jural postulate called the “amoeba-like way of thinking” may be drawn from the specific postulates; it is a general postulate, one that allows people to behave so as to deviate from the regulation of official law without defying its authority. Owing to its flexible nature, the postulate enables people to adapt themselves to changing circumstances as a means of preserving their identity. For this reason the postulate is regarded as underlying Japanese attitudes toward law – such well-known attitudes as aversion to law, law undifferentiated from morality, indefinite conceptions of right and contract, and the like. Referring to evidence of similar postulates in reports from various societies, both non-Western and Western, the conclusion is drawn that unofficial jural postulates function generally in the law to, justify apparent deviance or departure from official law; the unofficial jural postulates vary in flexibility, and this variance is a reflection of cultural characteristics of the societies in which they function.