A radio wave transmission/reception device capable of detecting an obstacle in front of a vehicle using radio waves is disclosed. The device includes a radio wave transmission/reception unit; a radio wave reflection unit installed around the radio wave transmission/reception unit and changing the direction of the radio waves such that the radio waves can be propagated forwards from the vehicle; a radio wave rectilinear propagation guide unit installed in front of the radio wave reflection unit and guiding rectilinear propagation of the radio waves; and a viewing window installed in front of the radio wave rectilinear propagation guide unit and oriented toward the radiator grille. The radio wave rectilinear propagation guide unit has an inductive film parallel to the viewing window, with at least a reflection protrusion formed on the inductive film. The device improves the rectilinearity of radio wave propagation and improves the appearance of the radiator grille.