Abstract: A hydrogen generating material reacts with water to produce hydrogen and includes at least one metal material selected from the group consisting of aluminum, magnesium, and their alloys. The metal material includes particles with a particle size of 60 ?m or less in a proportion of 80 wt % or more. The hydrogen generating material can produce hydrogen easily and efficiently at low temperatures. A hydrogen generator can be made portable by using the hydrogen generating material. Moreover, the use of the hydrogen generating material as a hydrogen fuel source can reduce the size of a fuel cell and improve the electrical efficiency.