To provide a method and apparatus for the crystallization of an organic compound through adiabatic cooling, which can attain a reduction in operation and equipment cost. [MEANS FOR SOLVING PROBLEMS] In a crystal tank (20), an organic-compound liquid mixture which contains a refrigerant is subjected to an operation for adiabatically cooling and vaporizing the refrigerant. The crystal slurry produced by this operation is discharged from the crystal tank (20). The vapor generated is pressurized with a compressor (30) to a pressure not lower than the operation pressure in the crystal tank (20) and led to an absorption condenser (10). In the absorption condenser (10), the pressurized vapor is cooled and condensed while keeping it in contact with a solution of the organic compound. The liquid resulting from this absorption/condensation is finally led to the crystal tank (20).