Mixers are used in various industrial fields where they are necessary to intimately mix two reactants in a short period of time. However, despite their widespread use, complex unsteady flow characteristics of industrial mixers are not systematically investigated. The present study aims for clarify unsteady flow characteristics induced by various impellers in a tank. Impellers are hydrofoil turbine, neo-hydrofoil turbine and pitched blade turbine(PBT) types. A high speed CCD camera and an Ar-Ion laser for illumination were adopted to clarify the time-dependent flow characteristics of the mixers. The rotating speed of impellers increased from 6Hz to 60Hz by 6Hz. The maximum velocity around pitched blade turbine impeller is higher than the other type impellers. These three types of turbine show that typical flow characteristics of axial turbine and suitable for mixing high-viscosity materials.