To provide a structure wherein an air drier is manufactured in a space-saving manner at a low cost by a method wherein two heat-exchangers of one being a heat-exchanger to dehumidify drain in compressed air and the other being a heat-exchanger to effect reheating are integrally constituted.

Compressed air enters through an air inlet 2 of a heat-exchanger 1 for reheating compressed air and is subjected to a primary heat-exchange with air discharged from a drain separator 3. In this case, respective air is partitioned from each other by a plate 6 in a manner not to be mixed together. Primary heat-exchanged air then enters through an air intermediate inlet pipe 5 of a heat-exchanger 4 for dehumidification and is cooled and dehumidified. A refrigerant effects incoming through a refrigerant inlet 7 and effects outgoing through a refrigerant outlet 8. In this case, air entering through a refrigerant air intermediate inlet 5 forms a counterblow to a refrigerant and undergoes heat-exchange therewith. Air cooled and dehumidified by the heat-exchanger 1 for reheating is discharged from a cooling air outlet 9, drain is separated by a drain separator 3, and effects incoming through a cooling air inlet 10 of the heat-exchanger 1 for reheating compressed air and flows to an air outlet 11.