The present invention provides a diaphragm attaching structure of an electrostatic capacity type pressure gauge which can achieve an improvement of a measuring precision by inhibiting a poor weld and a heat strain from being generated while restricting an increase of a cost with an easy manufacturing.The present invention is a diaphragm attaching structure of an electrostatic capacity type pressure gauge in which a diaphragm for receiving a fluid pressure is provided in a tensional manner on one end of a tubular case, and a fixed side electrode for picking up a deflection displacement of the diaphragm as a change of an electric capacity is provided within the tubular case on a side opposite to a pressure receiving surface of the diaphragm, wherein an outer peripheral edge portion of the diaphragm is formed thicker than a center portion thereof, and the thick outer peripheral edge portion is thermally molten to be welded and firmly attached to an end surface portion around the opening on the one end of the tubular case.