A magnetic RAM (MRAM) using a thermo-magnetic spontaneous Hall effect includes a MOS transistor formed on a substrate; a heating layer formed above the MOS transistor and connected to a source region of the MOS transistor; a memory layer having a data write area to which data is written, the data write area being formed on the heating means; a bit line formed on the data write area; an upper insulating film formed on the bit line and the memory layer; and a write line formed on the upper insulating film so that a magnetic field necessary for writing data is generated in at least the data write area of the memory layer. The MRAM writes or reads data using the fact that a spontaneous Hall voltage greatly differs according to the magnetization state of a memory layer, thereby providing the device a high data sensing margin.