We have developed an ALU based reconfigurable device called RHW (Reconfigurable HardWare) that is designed to work with the CPU to accelerate the computation-intensive part of the application by reconfiguring its data paths and ALUs optimized for the algorithm. It is also important to develop high performance operation unit library to utilize function cells of RHW efficiently. This paper describes the basic architecture of the RHW, high performance operation unit library and evaluation results.