On the 1968 Tokachi-Oki earthquake and its aftershocks, about 130 strong-motion earthquake records were obtained in the network of the Port And Harbor Research Institute. This report present the results of the abservatin on the main shock and the 3 major aftershocks.
　The accelerograms with the maximum accelerations larger than 20 gals are reproduce. On the records at the 4 nearest ports to the epicenters, response spectra and Fourier spectra have been calculated; those 4 ports are Muroran Port, Aomori Port, Hachinohe Port and Miyako Port. There include the digitized records on the main shock and the largest aftershock recorded at the 4 ports. All the accelergrams in this report were recorded on the SMAC-B2 accelerpgraphs.