PURPOSE: To provide a slime control agent adding device for cooling tower, capable of supplying the proper amount of slime control agent into water used in the cooling tower simply, easily and correctly while provided with simple structure and inexpensive.

CONSTITUTION: A slime control agent adding device is provided with a communicating pipe device 71, having an intermittent drip receiving opening unit 721 and connected to the water tank 6 of a cooling tower A, a bottle supporting unit 73, supporting a slime control liquid agent receiving bottle 75 above the device 70, and an intermittent dripping device 74, connected to the bottle 75 supported by the bottle supporting unit 73 and dripping slime control liquid agent intermittently into the intermittent drip receiving unit 72 of a communicating pipe device 70 connected to the bottle 75 supported by the bottle supporting unit 73.