Effects of high pressure in a range of up to 1.7 GPa on ultrafast energy relaxation of LDS698 (C(19)H(23)N(2)O(4)Cl) molecules in solution have experimentally been illustrated by a method of femtosecond time-resolved absorption spectroscopy. The rates of the intramolecular and intermolecular energy relaxations show quite different pressure dependences. The observed results are in good agreement with the theoretical interpretation based on the pressure influences on the molecular energy gaps, the intermolecular H-bond interaction, and the solution viscosity.