PURPOSE: To improve the water permeability of road by a method in which grooved concrete blocks are placed on the base by connecting their grooves, a heating wire is set in the grooves, and concrete blocks are set on the grooved concrete blocks.

CONSTITUTION: A base 2 is formed, a given thickness of cushion sand 4 is placed, and grooved concrete blocks 3 are placed on them, where grooves 3B formed on the flat square body of the block 3 are connected with projections 3D and recessions 3C formed on left and right-handed sides. After a heating wire 5 is set in the grooves 3B, cushion sand 6 is placed on the blocks 3, and concrete blocks 7 are placed on the sand 6. Water permeability can thus be sustained to allow surface water to return to the underground.