Abstract: A diaphragm for electroacoustic transducers including loudspeakers as formed substantially in a dome shape having an outer periphery of a circular shape and made excellent in tone quality is provided. The dome shape of the diaphragm has an irregular section with a central arcuate edge line of a radius of curvature across the circular outer periphery and passing through an apex of the dome shape, and side surfaces formed on both sides of the central edge line respectively to have side edge lines intersecting at right angles the central edge line and having a radius of curvature larger than that of the central edge line. The side edge lines of both side surfaces are of constant radius of curvature at least in one of the surfaces or of mutually equal radius of curvature at all positions intersecting the central edge line, to be mutually asymmetric or symmetric for dispersing resonating portions over the whole area of the dome shape.