To provide a liquid treatment device capable of effectively magnetizing a liquid.

Supporting plates 28 are fixed to a housing 21. A shaft 23 is rotatably supported to each supporting plate 28 via each bearing 29. The shaft 23 is passed into a hole provided at a pole plate 24, magnets 25, covers 26 and a spacer 27. The two magnets 25 are covered with the bottomed cylindrical covers 26. The outsides of the pole plate 24, the magnets 25, the covers 26 and the spacer 27 are provided with spiral wire rods 30 composed of magnetic substance. The outsides of the spiral wire rods 30 are provided with coil supporting plates 31. A coil 32 made of a copper wire is wound round the coil supporting plates 31.