Abstract: An anti-surge valve opens or closes a path depending on a negative pressure formed at an intake manifold, and includes an operating unit movable in a direction in response to the negative pressure, a spring means provided to push the operating unit in a direction opposite to the moving direction of the operating unit in response to the negative pressure, a spring mounting portion for mounting the spring means, and a diaphragm disposed to cover an outer surface of the operating unit. The diaphragm may be formed in a substantially hollow cylindrical shape and include a circumference portion formed along a circumference of an opened top surface of the diaphragm, a coupling portion formed along a circumferential direction from an outer end of the circumference portion, and a side portion extended substantially vertically from an inner end of the circumference portion, and has substantially uniform outer and inner diameters.