It is possible to stably supply an electric signal to an ultrasonic generation element without causing friction or damage on parts or without requiring periodical parts exchange. A reception coil (11) connected to a vibrator (6) is wound on the outer circumference of a housing (1) constituting a shaft (30) of a machining spindle (101). The reception coil (11) is surrounded coaxially by a transmission coil (12) at an appropriate interval. A predetermined electric signal outputted from an ultrasonic drive device (21) for driving the vibrator (6) is applied to the transmission coil (12). The predetermined electric signal may be applied to the vibrator (6) via the reception coil (11) by electromagnetic induction between the transmission coil (12) and the reception coil (11).