Recently, biorefinery-derived cellulose nanofiber (CNF) products have been extensively utilized. Chemical pulp fiber is the main raw material in the production of CNFs, while recycled pulp fiber can also be used. In this study, CNFs were prepared from recycled pulp fiber by the aqueous counter collision (ACC) method as a nano-engineering mechanical treatment. Scanning electron microscopy observations showed that the width of the CNF from the recycled pulp fiber was less than 100 nm and decreased with an increase in the number of the treatment. The FT-IR spectra and X-ray diffraction profiles of CNFs from the recycled pulp fiber showed the same molecular structure and cellulose I with the same degree of crystallinity compared with CNFs prepared from the virgin pulp fiber.