As the interplate Kanto earthquakes along the Sagami trough, central Japan, three events are known in 1923, 1703 and 1293. For disclosing an event between 1293 and 1703, I investigated two candidates of the Kanto earthquake in the 15th century historiographically. The 1433 Eikyo earthquake, the first candidate, was felt strongly and caused damage in a wide area of the Kanto district, and was probably felt in Kyoto. At Kamakura on the northeastern coast of Sagami Bay, many aftershocks were felt for about twenty days, landslides occurred, and all earthen fences fell down. Hearsay in Kyoto tells that in Kanto buildings fell down and many people died. I estimated the seismic intensity at Kamakura at least at 5 Upper to 6 Lower (on the JMA scale) and that at Yamanashi-shi about 90 km northwest of Kamakura, at 5 Lower to 5 Upper. By adopting these estimations to a ground motion prediction equation, a probable source region has been inferred to be almost the same as that of the 1923 Kanto earthquake and M, around 8. However, there is no reliable record of tsunamis, although hearsay in Kyoto tells that the Tone River emptying into Edo Bay connected to Sagami Bay flowed backward, which suggests a tsunami run-up. If the Eikyo earthquake produced no tsunami, it is considered an inland event between Kamakura and Yamanashi-shi. I checked the possibility that the Isehara fault, the most probable source in terms of geography and its activity history, had generated this earthquake. The possibility turned out low because the predicted seismic intensity at Yamanashi-shi was 4. The 1495 Meio earthquake, the second candidate, has been suspected to be a great Kanto earthquake based mainly on a presumable tsunami deposit dated to the late 15th century found at Usami archeological site on the west coast of Sagami Bay. However, there is no record of this earthquake in contemporary historical documents in the Kanto district except for strong ground motion and a tsunami at Kamakura written in a brief chronological table (Kamakura onikki). It is uncertain whether the earthquake was felt in Kyoto though two contemporary diaries in Kyoto record earthquakes on the same day. Moreover, the event deposit at Usami has problems; marine diatom fossils have not been checked yet, and it is reported that the deposit did not contain ‘Ogama’ potteries widely used since around 1485 even though many fragments of potteries of the 15th century were contained. Therefore, it seems almost impossible that the 1495 Meio earthquake was a great Kanto earthquake. If the 1433 Eikyo earthquake is surely an interplate event, it becomes that a Kanto earthquake recurred only 140 years after the 1293 event, which brings about a significant problem for the present earthquake countermeasures. For unquestionable confirmation of the 15th century’s Kanto earthquake, more paleoseismological investigation is needed. Especially, a further study of the Isehara fault and searching for tsunami deposits in the 15th century are very important. Re-examination of the Usami event deposit is also indispensable.