A method of preparing a catalyst for hydrogenation of a hydrocarbon oil, wherein an aqueous solution containing a metal of Group VI of the Periodic Table and a metal of Group VIII of the same, along with a hydroxycarboxylic acid and optionally phosphoric acid is added to a carrier substance consisting essentially of at least one of an inorganic oxide and an inorganic hydrate, and the resulting blend is kneaded, shaped and thereafter dried at a temperature not higher than 200.degree. C. The catalyst has a high catalyst activity and is used for hydrogenation of a hydrocarbon oil, especially satisfying the requirement of reducing the sulfur content in a light oil.