A diaphragm pump, in particular a microdiaphragm pump, has a crank drive (1) with a connecting rod (2) and an elastic diaphragm (3) joined to the connecting rod (2). At its rear side opposite to the compression chamber, the diaphragm (3) is provided with at least one undercut fastening hole (8) into which the matching fastening end of the connecting rod is inserted. In order to secure the diaphragm (3) as accurately as possible on the connecting rod (2), so that neither radial nor axial forces can move it out of its position relative to the connecting rod (2), and so that the diaphragm (3) is exposed to as little as possible additional flexing work, the connecting rod (2) has at its fastening end a supporting surface (4) for supporting from below the central diaphragm area which is provided with a supporting surface (5), and one or several fastening projections (6) which extend in the axial direction of the connecting rod (2) over the supporting surface (4) of the connecting rod (2) form-fittingly engage the central diaphragm area provided with at least one fastening hole (8).