PURPOSE: To provide a device for being capable of individually and easily measuring at a site horizontal and vertical water permeabilities of a permeable ground by means of an extremely simple constitution.

CONSTITUTION: A device comprises a water permeability measuring cylinder 1, which is imbedded in the ground 2 to be measured, and a water feeding tank 6, which feeds water in the measuring cylinder 1. The water feeding tank 6 is composed of a cylinder 8 with a bottom, a water feeding pipe 9 standing vertically at the cylinder, a cover plate 10 covering an upper end part of the cylinder 8 with a bottom, an air drain 12 with a switch cock 11 bored in the cover plate 10, a water outlet port 7 placed at a lower part of the cylinder with a bottom, and a water gauge 13 indicating a water level in the cylinder with a bottom. When a cylinder with a bottom having holes at the side is adopted as the aforesaid water permeability measuring cylinder 1, a horizontal water permeability can be measured, and when a bottomless cylinder having no holes at the side is used, a vertical water permeability can be determined.