To provide an angle grinding device capable of extremely facilitating attaching/detaching of a grinding wheel, shortening attaching/detaching time by tens of seconds and safely performing angle grinding.

This angle grinding device 1 for supporting and rotating the grinding wheel 2 at a desired angle and forming a flat surface of an arbitrary angle on a workpiece 50 is provided with a grinding wheel arranging part 3 for arranging the grinding wheel 2, a grinding wheel mounting part 5 provided on the grinding arranging part 3 and having a first screwing part 4 and the grinding wheel 2 having a second screwing part 6 constituted so as to be screwing possible or screwing releasable with the first screwing part 4 and so as to be attachable/detachable to/from the grinding wheel mounting part 5.