The Purpose of this Study is to find the Modern Movements which had done important roles on the development of modern church architecture and sacred art in the first half of 20th century. I had investigated the background and process of the movements, and analyzed the buildings which represented the movements. And I compared the architectural fruits of 'Riturgical Movement' and 'L' art Sacré Movement. The results are summarized as follows : First, there are two important movements in Catholic church in the backgrounds of the innovative changes of modern church architecture, Those are 'Riturgical Movement' which pursuits to establish a closer relation between clergy and congregation, and to make the positive participants in the service not mere observers and 'L' art Sacré Movement' which pursuits to accept modern secular art into church. Second, both movements had been developed on the bases of the theological studies with tow monasteries - Benedictine Order and Dominican Order - as leader. And the main concept was a kind of revival movement which recovers the Christian tradition. Third, The two movements began from the different themes and in the different regions. But they exerted influences each other, and achieved successful fruits in the Catholic churches of England and Swiss in 1960'. Fourth, 'Riturigical reformation' and 'Acceptance of modern art' had been officialized and generalized through the second Vatican Council(1962-1965).