To obtain a hydrogenated 1,2-polybutadiene having a proper melting point, excellent in thermal aging properties and useful for an industrial goods, etc., by hydrogenating a highly crystalline syndiotactic 1,2-polybutadiene resin.

The objective hydrogenated 1,2-polybutadiene preferably has 10-70% rate of hydrogenation and 60-120°C melting point. For example, the hydrogenated 1,2-polybutadiene is obtained by dissolving or dispersing a syndiotactic 1,2-polybutadiene resin in an organic solvent such as n-pentane under an inert gas atmosphere, and blowing hydrogen gas in the solution or the dispersion in the presence of an organic compound of nickel or cobalt, and an organic aluminum such as trimethylaluminum at 40-200°C under a pressure between a normal pressure and 100kg/cm2 to hydrogenate the syndiotactic 1,2-polybutadiene resin.