Abstract
When negentropy is applied to a system under a general situation, it is shown in the preceding report that negentropy should be defined by Kullback-Leibler information, for, if it is defined by the difference of entropies, or by the entropy with the inverse sign, it may become negative under the general situation. Negentropy represents the potential of work, and the present report also shows from this point of view that the negentropy defined by Kullback-Leibler information is more appropriate than that defined by the difference of situation that an isothermal system is given, the maximum work which can be taken out of the system under this situation is proportional to the negentropy defined by Kullback-Leibler information, and if the system is not isothermal, infinitesimal changes of these quantities are proportional.
