PURPOSE: To continuously perform processing for a long time without any replacement of a wire-like drill so as to drastically improve accuracy and efficiency of a fine narrow hole machining in the work in an ultrasonic machining device for forming a fine narrow hole in the work, while providing ultrasonic vibration to a wire-like drill.

CONSTITUTION: An ultrasonic machining device comprises a long wire-like drill 1 which has an end abuts on a work and advancingly/retreatingly penetrates in a guide pipe 6, an ultrasonic vibrator 10 through which the guide pipe 6 is penetrated, and a drill feed means 20 which is fixed to the end of the ultrasonic vibrator 10, continuously feeds the wire-like drill 1 from the inside of the guide pipe 6 to the work, and fixedly holds the wire-like drill 1. The drill is continuously fed to the work according to abrasion of the wire- like drill 1.