Seven teleseismic long period P-wave records from World-Wide Standard Seismograph Network (WWSSN) are used to infer the source rupture process of the July 23, 1978 Lanhsu, eastern Taiwan earthquake through the body-wave iterative deconvolution method (Kikuchi and Kanamori, 1982; 1986). Results show that the rupture sequence consists of one main event and one largest subevent near the hypocenter determined by Pezzopane and Wesnousky (1989) and numerous smaller ones at a distance from the hypocenter. Comparison of the spatial distribution of mainshock rupture sequence with aftershocks shows that aftershocks are located in the area which did not break before the occurrence of the above-mentioned events. The total seismic moment of the three largest events is 8.76 x 10^26 dyne-cm.