The purpose of this study is to clarify the soils thermal conductivity dependency on water content. In this study, thermal conductivity tests were conducted for three types of soils under different moisture content using a thermal probe method. Water retention tests were also carried out in order to examine the effect of moisture content in the thermal conductivity of soils. Based on experimental results, it was revealed that soils thermal conductivity dependency on water content differed depending on the water retentivity characteristic of soils. The relationships between moisture content and thermal conductivity in the three types of soils are not linear, and it was observed an inflection point in each relationship. This indicates that thermal conductivity of soils depends on whether pore water, which contributes to conduct heat, is structurally continuous. Therefore, soils thermal conductivity dependency in water content can be explained by the structural configuration of pore water in the soils.