The Post and Drainage Hole Digger is designed to manually dig shallow holes in the earth for posts or deeper holes for drainage or shallow wells. It is a modification of an existing device called an earth anchor used for anchoring situations such as storage sheds and guying applications. The invention is comprised of a steel disk screw mechanism, a steel shaft to which the steel disk is welded at one end and an attaching mechanism is incorporated at the other end, a U-shaped steel cutting bar welded to the shaft and the disk, a steel cutting tooth bent downward and welded to the disk, a detachable turning handle connected to the shaft via the attaching mechanism, and extension(s) that can be inserted between the main shaft and the turning handle.