Pressure dependence of optical absorption spectra were measured for (phthalocyaninato)-nickel hexafluoroarsenate, NiPc(AsF6)(0.5) and (phthalocyaninato)-cobalt hexafluororarsenate, CoPc(AsF6)(0.5). We found a charge transfer from the central metal ion to the macrocycle at 0.5 GPa in NiPc(AsF6)(0.5) and 1.1 GPa in CoPc(AsF6)(0.5). According to the electron-filling process in the pi-conduction band, a metal-insulator transition and an evolution of the energy gap was observed in NiPc(AsF6)(0.5). On the other hand, nonmetallic CoPc(AsF6)(0.5) showed a continuous change.