Geochemistry of groundwaters in granitoids of Japan and those of Baltic and Canadian shields was reviewed in order to construct a basis which is available for future extraction and investigation of thermal anomaly and hydrothermal waters in granitic areas without volcanic activity. Groundwaters in granitoids derived from meteoric water are generally Ca•Na-HCO3 type, low in salinity (<1 g/l), slightly acidic to neutral and oxidized at shallow levels and Na-HCO3 type, low in salinity, slightly alkaline (pH<10) and reduced at deep levels with the exception of more varied geochemistry at areas where fossil or present seawater has infiltrated or fluids derived from magma or hot rocks have been left. Groundwaters in the shields are generally Ca(•Na)-Cl type and highly saline (>300 g/l) at deep levels. The following tasks to be solved are necessary for more detailed understanding of geochemistry of groundwaters in granitoids: i) quantitative evaluation of water-rock interaction process using a geochemical simulator and ii) identification of origin, genesis and mobilization mechanisms for saline groundwaters at deep levels.