The picosecond regular reflection spectroscopy system was developed and applied to a beta-copper phthalocyanine pellet. On the basis of transient extinction coefficient change spectra obtained by Kramers-Kronig transformation, excitation energy relaxation processes were analyzed. A hot band due to a vibrationally excited state was confirmed to be the main transient species produced via exciton-exciton annihilation in the picosecond time range.