This invention provides a catalyst for partial oxidation of unsaturated hydrocarbon, characterized in that the catalyst comprises finely divided gold particles immobilized on a titanium-containing oxide and is one subjected to a silylating treatment or a hydrophobilizing treatment. The catalyst of the invention shows little deactivation with time in a reaction for preparing an epoxide from unsaturated hydrocarbon, and can stably retain a high selectivity, a high activity and like excellent catalytic capability for a long term.