Superconducting elements under high pressure

Developing room-temperature superconductor (superconducting at temperature higher than room temperature) is one of our goals of science and technology. Pressure is a powerful tool for investigation of superconductor to improve the properties and to synthesize the target material. Most of superconducting materials show a negative pressure dependence in the superconducting temperature, Tc. But some elements show the positive dependence at high pressure. We have been interested not only in the pressure effect on Tc but also in the onset of new superconductivity under pressures. Here we review the experimental investigations of pressure-induced superconductivity in elements with developments of high-pressure technique combined with low-temperature equipments.