Moisture is one of the important factors influencing mechanical properties of rock. Uniaxial compressive and indirect tensile strengths have been well known to vary from air-dried to water-saturated condition. However, in a uniaxial tension test, which has been difficult to be conducted with a water-saturated rock specimen, knowledge about the effects of moisture is insufficient; for example a complete stress-strain curve has not been obtained. In this study, the uniaxial tensile testing for an air-dried specimen was modified to obtain a complete stress-strain curve for a water-saturated specimen. Especially, bonding method between a specimen and loading platens was carefully reexamined and modified. By the modified testing method, complete stress-strain curves of two andesites, a granite and a tuff were obtained under water-saturated condition. Experimental results under the water saturated condition showed larger inelastic strain at peak strength than that under the air-dried condition. With a two-dimensional specimen model, crack extension in uniaxial tensile test was numerically simulated. Calculated results showed more cracks extension and larger inelastic strain under water-saturated condition as in the experiments.