The molecular-level identification of a chiral recognition process of phthalocyanine (Pc) was studied on a Cu(100) surface by scanning tunneling microscopy (STM). STM revealed that a chiral Pc molecule forms a series of metastable dimer configurations with other Pc molecules. Eventually, the Pc molecule recognizes another Pc molecule with the same chirality to form a stable dimer configuration. Homochiral dimers were found on the Cu surface, demonstrating the chiral specificity of Pc dimerization. The mechanism for this chiral recognition process is identified, disclosing the critical role of the particular adsorption geometry of the chiral dimers on the Cu surface.