Power consumption in an agitated vessel with an "EGSTAR" agitator, which has been practically used as a bioreactor, was measured under aeration. The power consumption of the "EGSTAR" agitator did not decrease so much with aeration, in contrast to the result of a disk turbine impeller. In the turbulent flow region of Re-d>300, the power number at a specified gas flow rate takes a maximum value. The correlations of the maximum power number Np-g,Np-R and the rotational speed N-R at which the power number takes the maximum are derived using both operating conditions and impeller dimensions. The power number under aeration Np-g in the range of N/N-R>1 in turbulent flow region is correlated with the rotational speed N, with help of N-R and Np-g,Np-R, as Np/Np-g,Np-R=(N/N-R)(-0.30) The combination of the correlation of Np-g above with the correlations of Np-g,Np-R and N-R gives rise to the following power correlation of EGSTAR agitator under aeration. Np-g=0.68N(A)(-0.08)Fr(-0.19)(h(d)/d)(0.01)(1-epsilon)Np-0.22,(R) The power consumption of EGSTAR agitator under aeration is not affected so much by gas flow rate, in contrast to the result of a disk turbine impeller.