This thesis questions the fundamentals and modes characterising the European architects' way of looking at Japanese architecture and garden art between 1870 and 1940. It establishes the corpus of the major writings and of other texts published by their Occidental and Japanese contemporaries in English, French and German. We analyse the writings' major issues, outstanding specifics and realisations. We detect and describe the creation of a modern Japan-ness through the writings of four major protagonists. Firstly, Josiah Conder was professor of Architectural History and Theory at Tokyo Imperial College and later considered as the "father of modern architecture" in Japan. We discuss his articles and books, published between 1877 and 1893, as being inaugural as well as forerunners of Japan-ness. Between 1903 and 1910, the architect Chûta Itô and the art historian Kakuzô Okakura gave its premises in their publications. The engineer Franz Baltzer as well as the architects Ralph A. Cram and Frank Lloyd Wright confirmed some of these ideas in their books published between 1903 and 1912. Secondly, we study writings from an architect who never traveled to Japan : Robert Mallet-Stevens. His articles, written in France from 1911 et 1913, were an indirect reference to Conder's articles. Thirdly, we analyse the theoretical and innovative works published by Bruno Taut between 1924 and 1937. We look at the way in which he valued and consolidated an intercultural Japan-ness. We question the existence of a Japan-ness in garden arts' writings. We establish how his contemporaries spread Japan-ness specificities : the architects Wajiro Kon, Kôji Fujii, Tetsuro Yoshida, Sutemi Horiguchi, Wells Coates, Richard Neutra and Antonin Raymond, the art historian Jirô Harada, the landscape designers – Tsuyoshi Tamura, Percy. S. Cane et Christopher Tunnard –, and the writer Jun'ichiro Tanizaki. We identify which specificities had already been defined by Itô, Kon and Horiguchi before Taut validation. Fourthly, Charlotte Perriand confirmed this established modern Japan-ness as a source of inspiration with her notes taken during her stay in Japan between 1940 and 1941. The thesis chronicles the impact of her notes onto some of her realisations in Japan and later in France. Thanks to this comparative analysis of texts, the thesis argues that the European gaze towards Japan is reflecting its preoccupations towards justifications for its own architectural development. This gaze is also orientated by the interests of the Japanese themselves. These are looking for an international recognition of their traditional architecture. We describe then how Japan-ness is created through writings and how it works as an appropriation of modernity enabling Japanese architecture to step in an avant-garde role. This creation follows two stages. The first one is a process of distinction from Asian architecture by identification and reinforcement of Japanese specifics. At its core lies the discourse upon the differences of the Japanese shintoist and zen soul. The second one is a process of sorting out common specificities with Western avant-garde ones. This time, the discourse concerns abstract similarities. The whole set of Japan-ness specificities defines an intercultural architecture which distinguishes itself both from Japonisme and from Occidentalisme. Lastly, the results show the profits gained by this European gaze and taken into account in their own architecture.