Activated carbon fiber (ACF) is used in new application fields as solvent recovery, water purification, capacitor etc. on the basis of its some unique properties which are different from those of the conventional granular or powder active carbon (AC). Further extension of application fields, the present author think, will be accomplished by supporting of an agent on ACF, because this is the most effective technique to create novel properties and functions. In this review, ACF was first characterized briefly by comparing with the conventional AC. Next mesopore formation techniques are explained because they must be a key to extend application fields of not only usual ACF but also agentsupported ACF. Some supporting techniques of an agent on ACF are discussed in regard to their advantages and disadvantages. Finally the practical application studies of agentsupported ACF in progress are introduced.