A method of manufacturing a compound semiconductor device comprises forming a scribed groove extending from an edge of a major surface of a laminated body to an internal region on the first major surface. The laminated body has the first major surface and a second major surface and is formed by crystal growth of a compound semiconductor multilayer film on a substrate. The scribed groove is shallow at the edge and deep in the internal region. The method may further comprise separating the laminated body into first and second portions separated by a separation plane including the scribed groove by applying load to the second major surface of the laminated body.