the present invention relates to a fluid agitator which may stir fluid in a closed space without leakage of the fluid . the fluid agitator has a motive means and a bearing means installed in the closed space . in the fluid agitator employing a electric motor as the motive means , only the stator coil of the motor which is weak in its resistance against high temperatures and humid atmosphere is sealed in a sealing chamber . the sealing chamber may be provided with a cooling device to cool the inside thereof . the driving shaft of the motor is supported by a bearing having resistance to high temperatures and high humidity and is provided with an agitating blade . in the fluid agitator employing a turbine system as the motive means , a turbine chamber and a turbine blade are set in the closed space . a fluid supply is furnished to introduce fluid into the turbine chamber from outside of the closed space for driving and rotating the turbine blade . the turbine blade is connected to an agitating blade through a rotation transmission .