To provide a drain device for ground sufficiently adaptable even to multiple layers of aquifers and capable of enhancing draining efficiency in spite of an air jet well method by enclosing an inner pipe for pumping and an air pipe for air supply in an outer pipe, and a drain method for ground using the drain device.

This drain device comprises an outer pipe 11, an inner pipe 12 in which the outer pipe 11 is installed, and an air pipe 13. The air pipe 13 is opened upward to the throat part of a venturi V at the lowermost part of the inner pipe 12.