PROBLEM TO BE SOLVED: To provide a manufacturing method of a bimorph type piezoelectric actuator which enables long life, a switching device, a transmission path switching device, and a testing device.SOLUTION: A manufacturing method of a bimorph type piezoelectric actuator includes: a first piezoelectric element layer formation stage where a first piezoelectric element layer is formed on a substrate; a support layer formation stage where a support layer of an insulator is formed on the first piezoelectric element layer; a second piezoelectric element layer formation stage where a second piezoelectric element layer is formed on the support layer; and a removal stage where a part of the substrate is removed to form an actuator having the first piezoelectric element layer, the support layer, the second piezoelectric element layer.