The deteriorations of highway bridge concrete slabs that were constructed during the high economic growth period have become apparent. One of the efficient maintenance measures for these deteriorated slabs is to replace them to new slabs. In this study, authors proposed the Precast UFC Slabs that are lighter than existing slabs, and the new joint system using PBL between slabs and steel girders in order to make a rapid construction. This paper described about the several load bearing performances and fatigue durability of the Precast UFC Slabs by experimental approach. These results showed that sufficiency of their performances and durability for the replacing new Precast UFC Slabs.