An impulse generator including first and second differentiators coupled in parallel to each other, for generating impulses by differentiating a clock signal, and first and second switches for transiting on and off the first and second differentiators respectively to selectively output the impulses generated by the first and second differentiators, and varying polarity of the impulses by changing a direction of a current flowing through load. Accordingly, the negative and positive impulses are selectively output according to the circuit state, reliability of the impulses is improved, and power consumption is reduced.