PURPOSE: To provide a powder mixing-dissolving device for preparing solution of given concentration in which the consumption of powder can be minimized.

CONSTITUTION: A powder storing body 2 and a mixing-dissolving cylindrical body 3 are disposed on the upper side and lower side, and a power outlet 7a is opened at the lower section of the powder storing body 2, while an upper end opening of the cylindrical body 3 is located below the powder outlet 7a, and a water introduction pipe 12 for introducing water from the outside is attached on the cylindrical body 3. An end opening of the water introduction pipe 12 is opened toward the direction along the inner peripheral face of the cylindrical body 3, and a lower end peripheral wall 11 is formed on the lower side of the water introduction pipe 12 on the inner peripheral face of the cylindrical body 3, while the lower end opening of the lower side peripheral wall 11 is made to communicate with the lower end opening of the cylindrical body 3.