A process for producing an oxime is provided, wherein the process comprises the step of reacting a ketone, hydrogen peroxide and ammonia in the presence of a crystalline titanosilicate having MWW structure under the condition that the ammonia concentration in the liquid portion of the reaction mixture is about 1% by weight or more. By the process, an ammoximation reaction of the ketone can be carried out with a high conversion of the ketone and a high selectivity to the oxime corresponding to the ketone, thereby producing the oxime with a high yield.