A clam shell action post hole digger includes a pair of opposed movable shovel blades pivotally attached to a cross brace. A combination stationary shaft and an inner movable rod are secured to the cross brace. The rod and shaft each has a handle attached at the upper end to allow the rod to rotate within the shaft by causing the pair of handles to open and close by the user. An eccentric cam plate mounted at the bottom of the rotatable rod causes the pair of shovels to open and close. A spring and pair of locking tangs on the cam plate lock the shovels in the open mode. In an alternate, a locking bar secured to and extending below the cam plate locks the shovels in the open mode. In normal operation the pair of shovels are in the open digging mode. The blade edge on the bottom of each shovel allows the user to form a cylinder-shaped hole by turning and pounding the digger in the ground by gripping and turning the pair of handles. Loosened dirt can be removed by closing the pair of shovels to trap and scoop out the dirt at the bottom of the hole being dug.