We report magnetic susceptibility and electrical resistivity measurements under hydrostatic pressure up to 2 GPa on single-crystalline PrCu2, which exhibits the pressure-induced Van Vleck paramagnet-to-antiferromagnet transition at 1.2 GPa. The measured anisotropy in the susceptibility shows that the ordered 4f moments lie in the ac plane in the pressure-induced magnetic state. We propose that remarkable pressure effects on the susceptibility and resistivity are due to changes in the quadrupolar state of O-2(2) and/or O-2(0) under pressure. We present a simple analysis in terms of the singlet-singlet model.