In an operation cycle of Accelerator Driven System (ADS), effective multiplication factor (keff) largely varies with the burn up of fuel. The ADS is available to keep the core power be constant by changing the proton beam intensity. However, it is not good for an accelerator and high beam intensity results in the irradiation damage. In this study, we have investigated a method for controlling the keff by using a control rod of the metallic hydride (HfH1.3) which is expected to have longer life than an original B4C control rod of a fast reactor. For the core, burnup swing during an operation cycle, control rod worth for various locations of the control rods, core characteristic of the ADS core with the control rods were analyzed. As the result, it is found that the control rod of HfH1.3 has large worth enough to suppress the burnup swing. By using three control rods, it is confirmed that the operation of the ADS core with the constant keff is possible.