Ultrasonic longitudinal vibration and abrasive slurry are currently used in combination as an effective method for machining holes in brittle materials. However, the method of ultrasonic longitudinal vibration suffers from the disadvantages of low removal rate and low machining accuracy. We aim to resolve these issues by using ultrasonic complex (longitudinal-torisonal) vibration. Torsional vibration is considered to improve the processing of the hole side of the brittle materials such that the abrasive slurry can circulate more easily. We assume improvement of removal rate and machining accuracy for that reason. In this study, using soda-lime glass as the processed material, the machining time is measured to assess the machining characteristics of a hole (diameter: 8 mm; depth: 4 mm) created using complex or longitudinal vibration sources by varying the pressure during processing (0.50 – 2.25 MPa). As a result, the machining time when using a complex vibration source is notably shorter as compared with that using a longitudinal vibration source at the optimal processing pressure.