Provided is double-faced adhesive tape joining apparatus that allows accurate joining of a double-faced adhesive tape on a tape joining surface of a workpiece in a curved or bent shape with no damage on a surface of a separator joined to the double-faced adhesive tape and no floating of the separator. Specifically, a hand-operable base includes a tape guide for guiding the double-faced adhesive tape successively supplied, and a joining head for pressing against the joining surface of the workpiece the double-faced adhesive tape supplied to a front end of the base. The base and the joining head are configured as to rotate relatively about a support axis toward a longitudinal tape direction.