The boost dc-dc converters are used to increase the magnitude of dc voltage. The renewable energy sources such as photovoltaic and fuel cell generate low magnitudes of voltage. To solve this problem, it is necessary to use a boost dc/dc converter. In this paper, a new boost dc-dc converter by using coupled inductor is proposed. In the proposed converter, by choosing the sutitable value of the coupled inductor coefficient, it is possible to obtain minimum ouptut ripple. In the proposed converter as same as the conventional boost dc-dc converters by changing the value of duty cycle, the output voltage could be controlled. Finally, the accuracy performance of the proposed converter is reconfirmed thruogh the simulation results in PSCAD/EMTDC software.