In this study, an ultra-wide band (UWB) antenna having band-notched operation for WLAN application has been designed. To model the antenna design, HyperLynx (R) 3D electromagnetic simulation program is used. The UWB antenna operates between the frequencies of 2.5 GHz and 11 GHz. To obtain the ideal rejecting characteristic over the desired frequency band, a Y-shaped strip is added into the full UWB antenna radiator. Thus, a frequency rejection response is obtained in band range of 5.0 GHz and 6.0 GHz for WLAN application. By changing the size of the Y-shaped strip, not only center frequency for interval 5 GHz and 6 GHz but also rejected bandwidth can be readily shifted. As a result, A suitable notch characteristic is achieved for desired band thanks to optimized strip geometry.