A regenerator material is comprised of a granular body made of bismuth or an alloy of bismuth and antimony. A rate of the granular body having a grain size of 0.14mm to 1.6mm is 70% by weight or more with respect to the entire granular body, and a rate of the granular body in which a ratio of a major axis to a minor axis is 5 or more is 70% by weight or more with respect to the entire granular body. Thereby, there is provided a regenerator material, more friendly to the environment, easily turned into a spherical shape, having sufficient mechanical strength for use, low cost, and having a superior thermal property when used for a cryocooler.
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