A water molecule exhibits characteristic properties on the basis of hydrogen bonding. In the past decade, single water molecules placed in non‐hydrogen‐bonding environments have attracted growing attention. To reveal the fundamental properties of a single water molecule, endohedral fullerene H₂O@C₆₀ is an ideal and suitable model. We examined the electronic properties of H₂O@C₆₀ by performing single‐molecule measurements. The conductance of a single molecular junction based on H₂O@C₆₀ was found to be comparable to that of empty C₆₀. The observed values were remarkably higher than those obtained for conventional molecular junctions due to the effective hybridization of the π‐conjugated system to the metal electrode. Additionally, the results undoubtedly exclude the possibility of electrostatic contact of entrapped H₂O with the carbon wall of C₆₀. We finally concluded that H₂O entrapped inside a C₆₀ cage can be regarded as an electrostatically isolated molecule.