To recycle a part of a hydroxyapatite crystal discharged in a crystallization process of waste water containing fluorine or phosphorus as a seed crystal.

A recycling method of the hydroxyapatite crystal comprises introducing the waste water containing fluorine or phosphorus into crystallization means 10 including a fluid bed filled with the seed crystal of calcium phosphate, recovering a part of the generated hydroxyapatite crystal by passing it through a seed crystal material 12 to crystalize phosphorus on the surface of the seed crystal, classifying the recovered crystal into the size of the seed crystal when it is initially filled and recycling the particle size-adjusted crystal as the seed crystal. The apatite crystal has a crystal particle size of 2.5 mm or smaller when it is drawn, the seed crystal has the range of the particle size of 0.5 to 1.2 mm and the amount of the apatite crystal drawn of 5 to 10% is recycled as the seed crystal.