An adjustment mechanism. At least one guide track is connected to a base. At least one spring is fit on the guide track. A slider is fit on the guide track. The spring is abutted between the base and the slider. A fixed member is fixed to the base. The slider is slidably disposed between the spring and the fixed member. A displacement adjustment bolt is screwed in the fixed member. A first rotator is fit in the slider and includes a section. A second rotator is fit on and engages the first rotator. The second rotator abuts the slider. A fixing bolt detachably abuts the second rotator and is detachably fastened to the first rotator. An adjuster is connected to the first rotator, adjusting the position of a target.