Lotus-type porous magnesium with a large number of unidirectional cylindrical pores was fabricated by unidirectional solidification of melt dissolving hydrogen in a pressurized hydrogen atmosphere. The vibration-damping capacity of the lotus-type porous magnesium plate which has many open pores was measured in this work. The attenuation coefficients of the free vibration of lotus-type porous magnesium were measured by hammering-vibration-damping test, which revealed that the attenuation coefficients increase with increase in porosity; the damping capacity of lotus magnesium is higher than that of non-porous magnesium. The mechanism for high damping capacity was analyzed on the basis of the Fourier transform technique, which indicates that various vibration modes of high frequency are observed. The excited vibrations of high frequency enhance the damping capacity of lotus-type porous magnesium.