Abstract: On board hydrogen storage and transportation of hydrogen are one of key issues to introduce hydrogen energy to the society. Hydrogen storage materials provide hydrogen storage means that work at ambient hydrogen pressure and temperature. Controlling of the reaction heats is needed for application of hydrogen storage materials. Mechanism of hydrogen storage includes adsorption on the surface, absorption into the solid and chemical reaction between materials and hydrogen gas. Hydrogen absorbing alloys, alanates such as NaAlH4 and some kinds of carbon materials are explained.