The frost shattering of rocks was explained by a frost heaving mechanism with coupled flow of heat and moisture in porous rocks during freezing. The pore-water pressure profiles of the freezing rock were obtained using tensiometers. Pore-water pressures of porous rocks during freezing were monitored by the transducers connected to tensiometers. Both the profiles of temperature and pore-water pressure were obtained simultaneously. From pore-water pressure measurements ahead of the freezing front, the large negative pore-water pressure is suggested as the major driving force responsible for water uptake in porous rocks. Migrated water accumulates in the frozen layer as ice-lenses formation causing the breakdown of rocks.