A pulsation damper mounted in a fuel chamber (23) of a high-pressure fuel pump (20) is provided with a diaphragm (11) having a flat section (11a) displaced when fuel pressure is applied thereto, a pump cover (10) for supporting the diaphragm (11), and a gas chamber (12) formed by the diaphragm (11) and the pump cover (10). Pressure pulsation occurring in the fuel chamber (23) is suppressed by displacement of the flat section (11a). The diaphragm (11) is formed in a closed-bottomed tubular shape with the flat section (11a) located at the bottom and has a projection (11b) provided to the periphery of the flat section (11a) and projecting to the side opposite to the pump cover (10). A tubular peripheral section extending from the outer periphery of the projection (11b) so as to be vertical to the flat section (11a) is fitted over the pump cover (10). The externally fitting portion of the tubular peripheral section is a joint section (11c) joined to the pump cover (10).