In recent years the requirement for reduction of energy consumption has been increasing to solve the problems of the global warming and the shortage of petroleum resources. For example in the power generation field, as the thermal power generation occupied 60% of the power generation demand, the improvement of the thermal efficiency is required considerably. To attain this purpose, heat transfer tubes used for a heat exchanger for recovering exhaust heat from gas turbine in combined-cycle type power generation must exhibit high heat transfer and low pressure drop. A spiral finned tube with an extended fin has recently been used for this purpose. This paper described that the effects of flow around fin on the heat transfer and pressure drop characteristics of the spiral finned tube banks used for the heat exchanger in the thermal power generation were clarified by measuring 3-dimensional velocity and turbulence intensity, temperature, and static pressure in the spiral finned tubes banks with different fin height.