To provide an oxygen water making method which enables the simple and easy making of oxygen water containing pure oxygen with a desired concentration, and an oxygen water making apparatus.

After a desired amount of drinking water W is stored in the water tank 2 constituting the oxygen water making apparatus 1 to hermetically close the water tank 2, air A in the water tank 2 and air A contained in the water W are vented by a venting device 8 so as to obtain an almost vacuum state and pure oxygen O supplied from an oxygen filling container 12 is discharged in the water W in the water tank 2 vented to the almost vacuum state to be mixed with or dissolved in the water W vented to the almost vacuum state, thereby making oxygen water OW which contains pure oxygen O with a desired concentration.