A nail gun of the present invention includes an adjusting portion which has elasticity. The elasticity of the adjusting portion is able to offset a thrust force of a nail pusher pushed by a magazine, so that a nail slot receives a nail only. The nail gun ensures not to shoot two sticks of nails simultaneously. The nail squeezes one side of the adjusting portion in a firing process so that the nail gun can provide sufficient space. Thereby when the nail is thicker, it can be shot by the nail gun. The present invention need not adjust by hand anymore for shooting different thickness of nails. The nail gun can not shoot two sticks of nails simultaneously.