© 2018, the Author(s). To utilize waste glass fiber-reinforced plastic (GFRP), we have created porous ceramics by mixing crushed GFRP with clay and then firing the resultant mixture. Some GFRP/clay ceramics have great porosity, which allows water to pass through them. In this study, by exploiting the high strength and water permeability of GFRP/clay ceramics, we aimed to develop water-permeable paving blocks that could prevent the inundation of roads by sudden heavy rains in urban areas. Various specimens were made by adjusting the mixing ratio of clay and crushed GFRP (40-60 mass%), the GFRP particle size, and the firing temperature. Bending strength, compressive strength, and permeability tests were then carried out on the samples. The obtained values were compared with those of porous ceramics made by mixing plastic without glass fiber and clay before firing. First, the difference in the porosity and strength of GFRP/clay ceramics and porous ceramics without glass fiber was clarified. Then, the manufacturing conditions of ceramics that satisfy both strength and permeability criteria were clarified for water-permeable paving blocks.