An optical lattice clock is one of the promising candidates for the next generation "SI" second. We developed an Yb optical lattice clock in 2009. The uncertainty of our Yb lattice clock will soon be limited by our cesium fountain clock. In 2009, we therefore started a new project on Sr/Yb dual optical lattice clock project. In this project we aimed to realize an optical lattice clock of Sr and Yb using the same vacuum chamber and to measure the clock transition frequency ratio with unprecedented precision. We believe that this project will strongly support the redefinition of the second using an optical lattice clock scheme.