A Herbert pendulum is a pendulum type hardness tester. In Herbert hardness test, the pendulum with indenter as a fulcrum swings on the specimen and swing angle of the pendulum is measured. Hardness is evaluated using logarithmic decrement (damping hardness). In this study, damping hardness of metals, ceramics and plastics are measured. Correlations between damping hardness and mechanical properties are clarified for metals, ceramics and plastics. Damping hardness of metals and ceramics decreases with increase Vickers hardness. However, correlation between damping hardness and bending strength cannot be observed for ceramics and plastics.