Deterioration of infrastructures and increase of its maintenance cost have been a worldwide issue, and Ground Penetrating Radar (GPR) observation is used for efficient maintanance. For bridge decks, detection of rebars inside bridge decks is important because they often become a trigger for damages. This research aims to reproduce 3D rebar mesh from GPR volume images based on 3D frequency filtering method. As a result, the proposed method reproduced 3D rebar mesh of a constructed test field in correct spacing. Also, it worked effectively for data of an in-service bridge.