PURPOSE: To prevent powder of magnetic cold heat accumulation material from being produced and improve the efficiency of a regenerator by a method wherein a mesh acting as a matrix of the regenerator is composed of hollow fine wires, which are filled with a metal of low melting point in its molten state and then magnetic cold heat accumulation material is mixed in the metal of low melting point at a specified ratio.

CONSTITUTION: Magnetic cold heat accumulation material 33 is mixed in metallic material 32 of low melting point and put in a hollow fine wire 31. From this fact, even if the magnetic cold heat accumulation material 33 is damaged by shock or the like, the power does not go out of the fine wire 31. In addition, since the magnetic cold heat accumulation material 33 is mixed in the metallic material 32 of low melting point kept at its molten and condensed state, even if the fine wire is broken, the powder can be prevented from going out of the fine wire 31. Thus, clogging by the powder of magnetic cold heat accumulation material 33 is prevented. Since the magnetic cold heat accumulation material is mixed in the metallic material 32 of low melting point at a specified ratio, it is possible to restrict rapid variation in temperature of a specific heat as an entire matrix by changing the mixing ratio.