The invention relates to an apparatus for separating a protective tape joined to a semiconductor wafer. Before joining a separation tape to a protective tape on a surface of a semiconductor wafer held, from its back side, by a ring frame via a dicing tape while pressing the separation tape against the protective tape with the use of an edge member, pure water is dropped from a piston nozzle onto the back side of the dicing tape located in front of a joining start end of the separation tape.