Volumetric water contents, θ, measured with various type of ECH2O soil moisture sensors (5TE, 5TM, EC-5, 10HS, ECH2O-TE, EC-TM) were evaluated for Toyoura sand, Andisol and Kanto Loam soils in Japan. The calculated value of ECH2O sensors reasonably estimated volumetric water contents for sand but underestimated for Andisol and Kanto Loam. It is necessary to independently calibrate the relationship between θ and ε obtained from each sensor for accurate measurements of θ for Japanese volcanic ash soils such as Andisol and Kanto Loam. The
soil water content measurements could be improved by us-ing the calibrated third regression equation with the deter-mination coefficient more than 0.95.