The steam invigoration of pitches (softening points 85 and 280 °C) homogenized with 1−3 wt % of organo rare-earth metal complexes such as Ln(C5H5)3 or Ln(acac) (Ln = Y, Yb) at 930 °C provided activated carbons with an extremely high mesopore ratio, >70%. The resulted activated carbon selectively adsorbs giant molecules such as vitamin B12, blue acid 90 dye, dextran, nystatin, and humic acid, reflecting their large mesopore volumes. To understand what kind of carbon skeleton in pitch is suited for generation of high mesopore ratio, the steam invigoration of a series of condensed polynuclear aromatics (COPNA) resins prepared from naphthalene, anthracene, phenanthrene, pyrene, or perylene and p-xylene-α,α‘-diol were conducted in the presence of rare-earth metal complexes. As a result, COPNA resins containing phenanthrene, perylene, and pyrene generated large mesopore volume.