'VALUE OF INFORMATION UNDER UNCERTAINTY'.

In accounting for information, the primal subject is how we should measure 'the value of information'. In this paper author first considers the uncertainty of information (without probability) under proper-uncertainty and gives the definition of it, based on the opportunity-cost-oriented approach. The 'uncertainty' of Range-restricting-type information is measured with 'the upper bound satisfactory enough' of the situation-elastic-value, and with the decrement of it the value of the R-type information is evaluated. The decision environment of quasi-uncertainty is also considered.