A nail blocking member for a nail gun. The nail gun includes a firing portion for firing a nail. When an object is pressed upon the nail blocking member by the firing portion, the nail is fired by the firing portion to enter the object. The nail blocking member includes a main body having a contact face, with a formation groove concavely disposed on the contact face, and a guiding block protruding from the formation groove. An object is pressed upon the contact face by the firing portion, and a nail is fired by the firing portion to enter the object to hit the guiding block, such that the nail is guided by the guiding block to move toward the formation groove, so as to be bent along the formation groove and reversely folded back into the object.