An embedded circuit board made without gas bubbles or significant internal gaps according to a manufacturing method which is here disclosed comprises an inner layer assembly, an embedded element, and first and second insulating elements. The inner layer assembly comprises a first main portion with opposing first and second surfaces, a first groove not extending to the second surface is positioned at the first surface. A first opening penetrates the second surface, and the first opening and the first groove are connected. The first groove carries electronic elements for embedment. The first insulating element covers the first surface and a surface of the embedded element away from the second surface. The second insulating element covers the second surface and extends into the first opening to be in contact with the embedded element.