One aspect of the present disclosure is a manufacturing device for a bent pipe. The manufacturing device includes an inner core metal placed inside a first pipe, and a tubular intermediate core metal placed between the first pipe and a second pipe. The intermediate core metal includes an intermediate core metal main body and a tubular first intermediate movable portion. The first intermediate movable portion is coupled to an end portion of the intermediate core metal main body, and swings about a first intermediate pivot axis relative to the intermediate core metal main body. The intermediate core metal main body includes an edge positioned closer to the first intermediate movable portion while the double pipe is bent. The edge intersects an imaginary plane orthogonal to a central axis of the second pipe at a position where the second pipe contacts the intermediate core metal.