The present invention provides a stable preservation method of a powdered soft drink preparation, which includes adding 0.2 to 1.0% by weight of a calcium oxide and 0.02 to 2.0% by weight of a particulate silicon dioxide in the powdered soft drink preparation containing a carbohydrate and a sour agent as a main component. The powdered soft drink preparation of the present invention maintains the original powder state, color and taste, which are obtained immediately after the production, for a long period of time without causing comparatively rapid coagulation of powders, discoloration and change in taste at the time of preservation.