The objective of the present invention is to dampen operating sounds of an electromagnetic drive mechanism used for a variable displacement to reduce an individual difference depending on apparatus due to the control mechanism in a high-pressure fuel supply pump change over time or installation tolerance.To achieve the above objective, the present invention is configured such that before the electromagnetic drive mechanism supplies a drive force to a plunger which is electromagnetically driven by the electromagnetic drive mechanism, another displacement force situates the plunger in a specific position. When compared to an occasion where the plunger is displaced all strokes by a magnetic biasing force, the above configuration is able to reduce the force of impact on a member (for example, valve body) mounted to the plunger and a restricting member, thereby damping the collision noise. Furthermore, since an extra member, such as a damping member, is not required, individual difference depending on apparatus do not easily occur.