Time-of-flight mass spectrometry and photodestruction spectroscopy have been carried out for cluster anions of benzene-water, Bz_m(H₂O)_n^-. We have found that a distinct magic number n = 6 is associated with all the species of m = 1-8 and that an intense photoabsorption of Bz_m(H₂O)₆^- occurs in the visible region. The results indicate that there is strong interaction between the excess electron and valence orbitals of benzene, suggesting that these cluster anions can be a new model for the scavenging process of solvated electrons in condensed phases.