In recent years, moisture sensors based on dielectric constant have played very important roles in real-time and nondestructive soil water monitoring. However, they tend to overestimate the soil water content with the increase of salt concentration. To accurately determine water content with dielectric sensors, the concentration-specific calibration would be required. This study proposes a calibration method of dielectric sensors considering the effect of salt concentration. Salt concentration can be measured with a four-electrode electrical conductivity sensor with relatively low cost. We developed calibration equations for both dielectric sensors and a four-electrode sensor. Both sensor output depend on water content and the electrical conductivity of soil solution. We thus solved simultaneous equations. Two different types of commercially available dielectric sensors were calibrated: the ECH₂O probe employed the capacitance method (Decagon Devices) and the ThetaProbe-ML2 employed the ADR method (Delta-T Devices). Calibration experiments were carried out using Tottori dune sand samples which were uniformly packed in covered containers at a constant temperature, for NaCl concentrations ranging from 0 to 31.9 ds/m, and for volumetric water content values ranging from 0 to 0.335 cm³/cm³. Results showed that solving simultaneous calibration equations allowed accurate estimations of water content for both the ECH₂O Probe and the ThetaProbe. This also means that the combination of the dielectric sensor and the four-electrode sensor enables simultaneous monitoring of water content and salt concentration in the soil. The ECH₂O probe was more inexpensive, but showed stronger dependence and nonlinearity on salt concentration than the ThetaProbe. Thus the fitted experimental equations of ECH₂O probe were more complex and estimation accuracy of water content was lower than the ThetaProbe. Considering high dependence of the ECH₂O probe on salt concentration, the ECH₂O probe needs simultaneous use of the electrical conductivity sensor in application to saline soil.