A magnetic refrigeration technology has been developed in all parts of the world. Altering the magnetic field around certain types of magnetic materials changes their temperature (magneto-caloric effect). We have conducted R&D to convert magnetic refrigeration technology, which uses this effect and is a highly-efficient, energy-conserving /environment-friendly technology, into practical application. In this special issue on magnetic cooling technology, the current state from system development concerning magnetic cooling technology to the magnetocaloric material development in Japan is introduced. In addition, the current state of the development of the Astronautics company who is the pioneer of magnetic refrigeration technology development is introduced.