We prepared Bi2Sr2Can-1CunOy (Bi-based) superconducting thin films by rf magnetron sputtering with the targets of Bi : Sr : Cu = 4.3 : 1.8 : 0.6 and Ca : Cu : O = 2 : 1, where sputtering gas of He and O2, and an off-axis geometry were used. From the result, we found that Bi2Sr2CuOy and Bi2Sr2CaCu2Oy films were able to be prepared by changing Ca-Cu-O content which we are controlled by the rf power of Ca-Cu-O target. Therefore, the Bi-based films with n≥ 3 are thought to be obtained by this method.