A filament web type precursor fabric for an activated carbon fiber fabric is produced by (i) spreading precursor filaments for preparing activated carbon fiber in a web state; and (ii) punching the precursor filaments for preparing activated carbon fiber spread in a web state to entangle the precursor filaments for preparing activated carbon fiber with each other. The filament web type precursor fabric has a structure in which the precursor filaments for preparing activated carbon fiber are spread in a web form and entangled with each other, and has a weight per unit area ranging from 50 to 500 g/m2. An activated carbon fiber fabric manufactured by activating the filament web type precursor fabric contains yarns with improved and uniform durability and crystallinity, and an shows improved performance of forming microfine pores having a diameter of 1 to 2 nm.