PURPOSE: To obtain a highly efficient and compact pulse-tube-type refrigerator having a refrigerating efficiency raised by an increase of a heating surface area and also having a pressure loss reduced, by using a cold head having a conical part provided in a low-temperature part.

CONSTITUTION: It is assumed that a cold head 32 has no conical part 31, but has simply a flat-plate part. Then a heating surface area is insufficient naturally and, in addition, the performance deteriorates due to a large friction loss generated by a shock wave occurring on the flat-plate surface of the cold head 32, since a fluid strikes on the flat-plate surface and then flows in dispersion to a cold storage material 36 when it returns from a heated end part of a pulse tube 35 to the cold storage material 36. When the fluid enters the pulse tube 35 from the cold storage material 36 through the flat-plate part of the cold head 32 in a reverse process to the above, it becomes a turbulent flow due to enlargement of the cross-sectional area of a flow passage, a pressure loss is caused thereby and efficiency lowers. In order to raise a refrigerating efficiency by an increase of a heating surface area and also to reduce the pressure loss, a cold head 32 being provided with the conical part 31 with a flow passage of the fluid is used.