Hydrogen embrittlement has been one of the biggest issues for usage of high-strength structural metals such as steels, Al alloys, Ti alloy and so on. The phenomenon has been figured out through the age, and has not been completely overcome yet. One of the reasons was that there were quite few techniques to detect hydrogen because hydrogen is the lightest and the smallest in the atoms. Recently, the techniques to detect hydrogen has been developed and advanced, and then provided important information on the state, the local position and the local concentration of hydrogen in the metals. This paper aims at the review of the techniques for detecting hydrogen associated with hydrogen embrittlement of the structural metals.