<;P>;PROBLEM TO BE SOLVED: To provide a horticultural water-holding agent with a small amount of which favorable water-holding property is brought so as not to cause growth inhibition nor rooting inhibition. <;P>;SOLUTION: The horticultural water-holding agent comprises highly water-absorptive resin where electric conductivity of a water-absorbing body when making 1 pts.wt. of the highly water-absorptive resin absorb 100 pts.wt. of ion-exchange water at 25°;C is 0-2.0 mS/cm, and the water absorption ratio of the ion-exchange water at 25°;C corresponds to 80-1,000 times. <;P>;COPYRIGHT: (C)2008,JPO&INPIT