This study confirmed the hydrogen embrittlement characteristics of API 5L X52, a natural gas pipeline material, and confirmed whether it is a suitable material for hydrogen gas use. In order to confirm the in-situ hydrogen embrittlement characteristics under a high-pressure hydrogen gas atmosphere, a slow strain rate test was conducted under a high-pressure hydrogen gas and nitrogen gas atmosphere. The thickness of the material used for evaluation was 15.9mm and a pipeline welded to 20 inch through submerged arc welding was used. The evaluation was carried out by processing specimens in the transverse direction at the base metal / weld metal part and processing it as a notch specimen based on ASTM G142-98. The evaluation was carried out when the temperature was stabilized at room temperature and pressure of 8 MPa for 10 minutes and the extension rate was carried out at a rate of 0.02mm/s ± 10%, which is the value shown in ASTM G142-98. As a result of the evaluation, in a high-pressure hydrogen gas atmosphere the tensile strength and elongation decreased due to hydrogen penetration through cracks during deformation of the material.