Nowaday, PEMFC using the metal hydride hydrogen storage tank attracts mobile fuel cell engineer’s attention though storage tank's weight is still heavy and pressure regulator is additionally needed. A pressure regulator especially for reducing the hydrogen gas pressure should be placed between the hydrogen storage tank and fuel cell stack because the stack operates usually under much lower pressure than the hydrogen charging pressure. The current commercial pressure regulator is not small size acceptable to mobile application like cellular phone because the commercial pressure regulator consists of bulky mechanical parts of metal material and uses the conventional fabrication methods, which is not easy to miniaturize the size of pressure regulator. However, if micro pressure regulator is realized on the silicon wafer, MEMS technologies for semiconductor fabrication such as etching, bonding, and dicing are established well and such various fabrication processes can be applied equally to make the micro scale pressure regulator on the silicon wafer. This paper presents the design, fabrication processes, and performance experiment data of small size hydrogen gas pressure regulator, whose gas inlet pressure is below 10 bars similar to storage tank’s charging pressure and outlet pressure of micro pressure regulator is designed to become less than 1 bar. Finally, the micro pressure regulator of 5mm x 5mm x 1mm dimension is successfully fabricated on a silicon wafer and its function is evaluated after the integration with dead-end stack as well as metal hydride hydrogen storage tank.