Abstract: The invention relates to a force supply mechanism and a nail gun having the same. The force supply mechanism includes a cylinder set inside the nail gun; a piston movably disposed in the cylinder; a nail striking member co-movably connected to the piston; and a spring unit disposed in the cylinder and located between the piston and the rear end cover of the cylinder and configured such that an engagement of the nail striking member with a driving member causes the piston to move backward in the cylinder to push the spring unit into a contract state to store energy therein, and an disengagement of the nail striking member with the driving member causes the spring unit to release the stored energy to push the piston to move forward in the cylinder so that the nail striking member is co-moved therewith to strike a nail out of a muzzle.