It seems to me that P. Sabatier, eminent scholar of the Franciscan studies, understimates the historical values of the life of St. Francis by St. Bonaventure. According to his opinion, when St. Bonaventure wrote his life of St. Francis, there was a serious opposition between the two extreme parties of Franciscan Order, namely spirituals and conventuals. St. Bonaventure stood between the two extreme parties as the intermediator. In this position he must do the wor,k of compiler and peace maker, and try to omit the materials, even true, which threatens to cause the dissension between the two parties. The result is that the compromise vanquished the trueth and so we can only have a vague impression of the image of St. Francis in this work. But nowadays Sabatier's opinion must be seriously examined in the light of the recent studies of the Franciscan history. According to R. B. Brooke and S. Clasen, the struggle between spirituals and conventuals had not yet come during the life time of St. Bonaventure It rather belongs to a later development. So then, we must reconstruct the meaning which this work has in the Franciscan history. This essay ascribe to the following opinions. The first is that his writings are not a mere abridgement of writings of Thomas Celano but has direct referrences to the contemporary oral traditions. Therefore, when we compare its materials to those of Thomas Celano's or later documents, we can surmise what were the movements of the oral traditions among the Franciscan Order. My second opinion is that his work was not primarily intended as an .intermediate between spirituals and conventuals, but we can surmise that his intention was really to ward off the censures of the seculars against Franciscan and other mendicant orders. The last thing to be noted is that St. Bonaventure tried to grasp the historical significance of the life of St. Francis against the background of the development of Christian spirituality In this regard it is noted that his view of history has some similarity with the eschatological predictions of Joachim of Fiore.