Disclosed is a multifunctional synthetic resin block for roads. The synthetic resin block includes a water permeable sheet configured as a synthetic resin block having a flat sheet shape so as to be laid on a ground, a block frame configured as a synthetic resin body taking a form of a rectangular frame, which is divided into multiple rectangular areas each having open top and bottom sides, so as to be installed on the upper surface of the water permeable sheet, the rectangular areas being filled with filler stones, and multiple corrugated plates each configured as a synthetic resin having a rectangular plate shape and arranged so that corrugations thereof are oriented perpendicular to each other so as to cover the rectangular areas of the block frame. The synthetic resin block provides almost all functions, such as a rainwater retention function, water permeation function, and anti-slippage function, at low cost.