The magnetization intensity of oceanic crust in the Northeast Pacific, Atlantic, and Southeast Indian oceans was calculated from marine magnetic anomaly data to investigate long-term variations in magnetization intensity with crustal age. The magnetization intensity was derived by two-dimensional inversion of the upward-continued marine magnetic anomalies. The principal magnetization intensity variations versus age are summarized as follows: (1) In all the oceans, a high magnetization intensity exists at the ridge crest, followed by a sharp decrease within 8 My, and a minimum is reached at 8--20 Ma; (2) in the Northeast Pacific and Atlantic oceans, the magnetization intensity gradually increases up to at least 70 Ma. This variation pattern is consistent with the previous results of NRM measurements of drilled rocks and inversion of marine magnetic anomalies in the South Atlantic. ¿ American Geophysical Union 1992