A slide valve apparatus for automatic application of surface pressure is configured to include a connection switching device (20) for switching a connection position of a drive device (7) and a slide case (4) between a first connection position (discharge position) during molten metal discharge and a second connection position (surface pressure operation position) during surface pressure application/release. As a result, the drive stroke of the drive device can be greatly reduced and the already installed drive device can be used as is when a SV apparatus is upgraded.