This paper presents a band pass filter for ultra wideband (UWB) communication systems. The Federal Communication Commission (FCC) authorized the commercial use of the UWB technology in February 2002. Where, the frequency range of the spectrum mask in an indoor environment is from 3.1 GHz to 10.6 GHz. To transmit digital information on the maximum of 1 Gbps using this range, the band pass filter with the same passband is indispensable. We have succeeded in development of the ultra wide-band pass filter (UWBPF). In this paper, we report the fundamental transmission characteristics.