Picosecond absorption spectra of the copper phthalocyanine solid/water interface were obtained by analyzing transient regular reflection spectra, on which photoexcitation relaxation dynamics at the interface was Elucidated. Photoelectron ejection from the phthalocyanine solid into water was induced rapidly, and the formed phthalocyanine cation-electron geminate pair recombined with a time constant of 10 ps. The vibrationally excited, electronically ground state was produced by dissipation of electronic energy through the recombination.