A holding device for an ultrasonic transformer having a diaphragm cup, in particular for a motor vehicle, includes the following: a housing to accommodate the diaphragm cup; a decoupling component to position the diaphragm cup on the housing and on a holding section in vibration-damped manner; and a filler material to connect the diaphragm cup and the decoupling component to the housing in a vibration-damped and sealing, form-fitting manner, the decoupling component sealingly filling a gap between an edge of an opening of the housing and the diaphragm cup, as well as a corresponding method.