Nucleation device, heat storage device, and nucleation method for heat storage material

A nucleation device for causing phase change in a heat storage material from a liquid state to a solid state, the nucleation device including: an elastic member including a plurality of annular portions with a ring shape wound in substantially close contact with one another, the elastic member being elastically displaceable such that adjacent pairs of the plurality of annular portions in substantially close contact with one another separate from one another; whereinthe heat storage material is caused to phase change by the elastic member elastically displacing while disposed in the heat storage material.