High pressure fuel supply pump for internal combustion engine

The invention discloses a high pressure fuel supply pump for an internal combustion engine, comprising: a cylinder (12), a plunger (2) which reciprocates within said cylinder to change the volume within the cylinder (12), a valve body (5) provided, in order to open and close a through hole (5A) for connecting the interior of the cylinder (12) with a low pressure fuel passage, on the downstream side of said through hole, a first spring (5a) for biasing the valve body (5) in a closing direction, an engaging member (201) installed on the side of said low pressure fuel passage to operate said valve body (5) to an opening position against force of said first spring (5a), a second spring (202) for imparting said engaging member (201) resisting force to the force of said first spring (5a), and an electromagnetic driving device (200) for releasing said engaging member (201) from the state engaged with said valve body (5) against the force of said second spring (202).