To form a crystal without any delay in manufacturing a crystal product using a heat exchanger and to prevent an entrance of a material from a blocking by deposition fixing of the crystal.

In the heat exchanger, a heat exchange is carried out via a cylinder 2 between a cooling medium circulating along the outer peripheral surface of the cylinder and the material sent inside the cylinder. The heat exchanger has a blade 65 scraping the crystal depositing by the heat exchange on the cylinder inner wall, and a pin 71 provided in the cylinder to disarrange the material. By providing such pin 71, a disrupting effect can be given to the material flowing in the cylinder. The disrupting effect is given to the material containing many scraped crystals, which can prevent the crystal to deposit or to join together to form a big lump. As the result, a flowability of the material in the cylinder is assured, the material flows in from the entrance smoothly, and is discharged from an outlet smoothly, and the crystal does not block the entrance.