The invention provides an angle tool holder to be disposed on an attachment attached to a spindle head of a vertical machining center and holding the angle tool holder to enable five-face machining of a workpiece. The angle tool holder denoted as a whole by reference number 500 has a shank 510 inserted to a spindle of the main machine, wherein a rotation of the shank 510 is transmitted via a gear transmission mechanism or the like disposed in a housing 540 so that the direction of a drive shaft thereof is varied orthogonally to thereby drive the angle cutter 520. An arm 550 connected to the housing 540 has three pull stud bolts 570 disposed thereon. The three pull stud bolts 570 are arranged at 90-degree intervals, and are clamped simultaneously by three collet chucks out of the four collet chucks disposed on the attachment unit for five-face machining.