A combined gear cutting apparatus includes a workpiece drive portion, a first processing portion holding and moving a first tool to a processing position for a workpiece, a second processing portion holding and moving a second tool to a processing position for the workpiece, and a control portion which includes a storage portion storing workpiece information indicating a configuration of the workpiece before first processing is performed, first tool information, second tool information and relative position information. The control portion includes a tooth groove configuration calculation portion calculating tooth groove configuration information of the workpiece based on the first tool information, the workpiece information and the relative position information obtained when the first processing is completed. The second tool is configured to move to a start position of second processing for the workpiece based on the tooth groove configuration information, the second tool information and the relative position information.