To provide a regenerator type refrigerating machine capable of reducing the total sum of a thermal loss induced by movement of gas present in a gap between an outer circumference surface of a displacer and an inner circumference surface of a cylinder and a thermal loss induced by reciprocation of the displacer in the cylinder, and capable of suppressing a reduction in the refrigeration capacity.

The refrigerating machine includes: a cylinder 11; a displacer 13 which is disposed so as to be able to reciprocate along the cylinder 11 and forms an expansion space 21 at one end in the cylinder 11 and which includes a refrigerant gas flow path 23 formed therein; and a cold storage material 17 housed in the refrigerant gas flow path 23 and storing cold heat generating when the displacer 13 reciprocates. In the displacer 13, an outer diameter at a lower temperature end is larger than an outer diameter at a higher temperature end at a room temperature. A thermal contraction percentage of the displacer 13 when cooled from the room temperature to an operating temperature is larger than a thermal contraction percentage of the cylinder 11 when cooled from the room temperature to the operating temperature.