Irradiation with 4.0 MeV protons at a dose of 5 10 1 6 cm - 2 was performed for a grain-aligned HgBa 2 Ca ( n - 1 )Cu n O y (n = 2,3) sample. Magnetization hysteresis loops in external fields up to 5.5 T applied along the c-axis for the irradiated sample became wider than those for the unirradiated sample, indicating introduction of pinning centers by the proton irradiation. X-ray diffraction and TEM studies indicated that the proton irradiation produced amorphous defects within irradiated grains. The shape of the amorphous defects are 16 thick along the c-axis and 220 long in average. It is likely that the amorphous defects due to the proton irradiation serve as pinning centers in the present HgBa 2 Ca ( n - 1 )Cu n O y (n = 2,3) samples.