We investigated the effect of hydrogen gas environment to 1300MPa tensile strength of chromium-molybdenum steel (JIS SCM435) with a sharp notched specimen. Tensile tests were carried out in hydrogen gas and in helium gas environments. In hydrogen gas environment, the specimen which was not exposed to hydrogen gas and the specimen which was exposed to hydrogen gas for 48h were used. A thermal desorption spectrometry (TDS) analysis was conducted, in order to decide the exposure time to hydrogen gas. As the result of tensile tests, the notch tensile strengths in hydrogen gas exposed specimens was stronger than that of in hydrogen gas non-exposed specimens. We also investigated the crack initiation of notched specimens in hydrogen gas and found that the crack initiation load at the hydrogen gas non-exposed specimen was lower than that of the exposed specimen.