The present invention provides an attachment to be attached to a spindle head of a vertical machining center for gripping an angle tool holder and performing five-face machining. An attachment unit 100 for five-face machining comprises a ring-shaped cylinder member 110 fixed to a lower portion of a spindle head, and a clamp unit 130 directly connected to a piston disposed in the interior of a cylinder member. The clamp unit 130 is equipped with four collet chucks 140 for gripping a pull stud bolt 270 disposed on an arm 250 of an angle tool holder 200 attached to a spindle and drives an angle tool 220.