The purpose of this study is to acquire knowledge to help elucidate the process to the establishment of music education at school for children with intellectual disabilities. Through analysis of research papers on music practices at Hachioji school for children with intellectual disabilities (1969-1980), I identify two essential elements in the process to the establishment of music education at school for them. 1) Teachers develop a music class based on the physical reception of music by the children and their physical expression, grasping the actual condition of the children. 2) Teachers systematize stages wherby children are led to the course instruction in order that every child can have musical abilities.