To suppress attenuation of radio waves by foam so as to transmit/ receive radio waves with a sufficient wave transmittance by forming a front grill positioned in front of a radar out of a resin including foam.

In an on-vehicle structure for a radar detecting a forward obstacle, a front grill 1 and an emblem 2 are formed of a resin 4 including foam when a radar 3 is arranged inside the front grill part based on a structure in which the emblem 2 is overlapped in the center of the front grill 1. As the resin 4 including foam, any of a foaming resin, hollow resin and honeycomb type resin can be used. In this on-vehicle structure for the radar 3, radio wave attenuation can be suppressed to the minimum because of foam when radio waves are transmitted/received through the front grill 1 and the emblem 2. A structure, in which a part of the front grill 1 is cut out and a plate made of the resin 4 including foam is installed in the cutout, may be used.