The dynamic solvent effect on the excited state intramolecular charge-transfer (ICT) reaction of 4-(N,N-dimethylamino)triphenylphosphine (DMATP) in alcohol solvents is examined by a high-pressure method. In order to deduce the solvation effect on the ICT reaction of DMATP, the picosecond time-dependent Stokes shift (TDSS) of coumarin 153 (C153) in alcohols is measured as a function of pressure. The resulting high-pressure solvent relaxation time (tau(s)) is in excellent agreement with the longest longitudinal relaxation time (tau(L)) of alcohols from low-temperature sources. In the low-viscosity region at low pressures, the rate of the ICT formation correlates with tau(s) (or tau(L)), while in the high viscosity region at high pressures, it becomes noticeably faster than tau(s) (or tau(L)).