A manufacturing method is provided for a fluid control apparatus, in which the flow of a fluid is controlled by bringing a diaphragm valve element into contact with or separating the diaphragm valve element from a valve seat. The diaphragm valve element may be a joint body that is a combination of (a) a seat member that makes contact with the valve seat and (b) a body member. The joint body is formed by machining a material joint body obtained by welding together a seat-member material which is a material for the seat member and a body member material which is a material for the body member. The welding is performed on contact faces of the seat-member material and the body-member material of the material joint body in a range wider than contact faces of the seat member and the body member of the joint body.