To provide a drainage system and a drainage method, which can prevent a large amount of groundwater from flowing out to a ground surface during earthquakes.

A drainage system includes: a plurality of hollow cylindrical drainage materials 20 with water permeability, which are inserted in the depth direction of the ground and buried; and a hollow water-collecting material 21 with water permeability, which is connected to a top part of each drainage material 20, which collects groundwater flowing into each drainage material 20, which brings about inward inflow of the groundwater flowing toward a ground surface, and which discharges the groundwater to a drainage destination from an opening provided at one end.