Abstract: A retrievable inside blowout preventer valve apparatus for use in blocking undesired upwardly flow in the bore of a rotary drill string during well drilling operations is disclosed. The valve apparatus is installed and retrieved from a subsurface receiver sub connected in the drill string by movement through the bore of the drill string. When shutting off upwardly flow through the bore of the drill string, the valve automatically operably secures and seals itself in the receiver sub. A wireline retrieving tool is used to release the valve apparatus from the receiver sub and to establish a connection therebetween for retrieving the valve apparatus with the wireline.