A reflection-type bandpass filter for ultra-wideband (UWB) radio data communications is provided. The reflection-type bandpass filter includes a substrate formed by laminating a conducting layer and a dielectric layer, and a microstrip line made of a conductor of a non-uniform width and provided on the dielectric layer. The width distribution of the microstrip line in the lengthwise direction is set such that the absolute value of the difference in reflectivity at the frequency f in the regions f 10.6 GHz and the reflectivity in the region 3.7 GHz≦f≦10.0 GHz is not less than 10 dB, and the variation of the group delay in the region 3.7 GHz≦f≦10.0 GHz is between −0.2 and 0.2 ns.