Objective We developed fiducial imaging‐guidance markers for the prostate with less imaging artifacts than currently commercially available markers. The aim of this study was to evaluate the imaging artifacts and potential usefulness and safety of these novel fiducial imaging markers in preclinical experiments. Methods We selected specific metal materials and a shape that can minimize artifacts in line with a license we obtained for a metal with a gold‐platinum (Au‐Pt) alloy composition that maximized artifact‐free MRI images. Both phantom and canine prostate tests were conducted in order to evaluate the imaging artifacts for three imaging modalities, MRI, CT and ultrasound, and the risk of migration of the markers from the site of insertion to elsewhere, as well as crushing. Results The newly developed Au‐Pt material had less imaging artifacts in the MRI, CT and ultrasound imaging modalities in comparison with current commercially available fiducial markers made from gold materials only. The Au‐Pt markers had sufficient strength and durability and were considered to be potentially clinically useful and safe markers. Conclusion The developed Au‐Pt markers could be potential tools for accurate lesion‐targeted, organ‐preserving therapies such as lesion‐targeted focal therapy and active surveillance in addition to conventional radiation therapies.