This study examined how the various garden forms introduced in the entire garden of Naumkeag were expressed, and in particular, how the modern style of the Naumkeag Garden was planned. The results are as follows. The Naumkeag garden has introduced various garden styles from China and Europe. This phenomenon appeared to be different from the features of the modernist garden that rejected historical style. The garden elements are introduced in detail and ornamental form, which is different from the characteristic of modernism that avoids such style. The introduction of new industrial materials, such as concrete and iron, has been actively incorporated and are the most visible characteristic of the modernist garden. It was confirmed that the role of the outdoor room, which is a characteristic element of the modernist garden, and garden elements were designed as the material filling the space. As a result, Naumkeag gardens are characterized by modernist style including the introduction of new industrial materials and functional aspects of garden elements. In addition, due to the influence of neoclassicism, garden styles from various countries were displayed. Nevertheless, the Naumkeag gardens are gardens to which Fletcher Steele introduced modernism, and it is evident that it played an important role in the birth and development of American modernist gardens.