An electron in materials with a negative electrical charge also behaves as a tiny magnet termed spin. A material therefore becomes a magnet when the majority of electrons have spins in one direction. In addition to this well-known phenomenon, recent researches are suggesting that some types of spin order should cause other extraordinary phenomena; spontaneous polarization of electrical charges (ferroelectricity) or difference in color of material between the front and back sides (directional dichroism) (Fig.). We will research spin arrangements by using X-ray which has wavelength with the same order as atomic spacing. Our studies on relationship between functions of materials and spin arrangements provide useful information for exploration of novel functional materials.