The present disclosure relates to a drilling worktable for manufacturing tube support plates of a steam generator constituting a primary system of a nuclear power plant. The drilling worktable includes a plate having a drill insertion groove formed to face a position at which a heat transfer tube insertion hole is drilled in a member to be processed. In addition, the present disclosure relates to a method of manufacturing tube support plates using the drilling worktable for manufacturing tube support plates. The method includes fixing the member to be processed after locating the member to be processed on the upper surface of the seating section, and drilling the heat transfer tube insertion hole in the member to be processed using a drill unit.