To provide a water-retaining bag for a cut flower provided with a backflow prevention device, to be attached to the cut end of a flower bunch or a cut flower to keep the freshness of the cut flower during transportation and effective for preventing the spill of water or a nutrition solution in the main body 1 from the insertion hole 4 in the case of accidental overturn of the flower bunch or the cut flower.

The cut end of the flower bunch or the cut flower is inserted into a flexible main body 1 (a main bag 2 and an insertion tube 3), water or an aqueous solution containing a nutrient is put into the main body and the stalk or bunch of the cut flowers inserted through the upper insertion port 4 is bound with a tape or string. The inner face of the main bag 2 contacting with the outer surface of the insertion tube 3 is bonded and integrated in a manner to form a tube with the inside of the insertion part. Moisture is sufficiently supplied to the cut flower from the water or the nutrient solution poured into the main bag 2. In the case of accidental overturn of the bunch during transportation, the water or the aqueous solution in the turned main bag 2 is flowed into the space 8 between the main bag 2 and the insertion tube 3 to reduce the strength of the current and prevent the spill out of water from the bag.