According to one implementation, an attachment for a machining apparatus includes: a copying guide in a machining apparatus side and an air supply passage. The copying guide has a through hole for passing a tool through. The copying guide is contacted to a copying mold placed in a workpiece side. The copying guide is attached to a spindle holding and rotating the tool. The air supply passage is adapted to supply air ejected toward the workpiece side through a clearance between the tool and the through hole.