To provide the fixed amount supplier of liquid capable of surely supplying the fixed amount of the liquid at a low cost by a simple structure, arbitrarily and easily setting a liquid supply amount and continuously and surely supplying the fixed amount of the liquid.

This fixed amount supplier is provided with a first tank 10 provided with a tank main body whose upper space can be tightly sealed for storing the liquid and a second tank 20 connected with the first tank by a communicating pipe 30. The first tank 10 is provided with a cylinder body 9 whose one end is immersed in the liquid stored in the tank main body and other end is communicated to the outside of the tank main body, the communicating pipe 30 is provided with a first stop valve 35 for controlling the movement of the liquid from the first tank 10 to the second tank 20 and the second tank 20 is provided with an ejection nozzle 50 for supplying the constant amount of the liquid stored in the second tank 20 while ejecting it and a second stop valve 55 for opening and closing the ejection nozzle. The second tank 20 forms the liquid surface of the same level as the opening part position 9b of one end of the cylinder body 9 immersed in the liquid stored in the tank main body of the first tank 10 by opening the first stop valve 35.