Provided is a safety lancet including a reload double prevention structure for preventing a sliding block having a lancet needle from being reloaded to obtain blood, thereby fundamentally preventing reuse of the safety lancet. In addition, the safety lancet guides the sliding block to be straightly discharged without shaking, thereby minimizing pain when the lancet needle is inserted into a skin. The safety lancet includes an outer case forming a space part therein, an inner case sliding along the space part of the outer case, and having a through hole in a front end thereof, and a sliding block coupled to the inner case to straightly move along an inner portion of the inner case, and elastically supported within the outer case by a coil spring, wherein the sliding block comprises a lancet needle having an end protruding from a front end thereof, and a pair of loading hooks on both sides of a rear end thereof to engage with engagement protrusions of the inner case. As the inner case is moved rearward, when the sliding block is disengaged from a portion of the inner case, the sliding block is moved forward by elastic force of the coil spring to temporarily expose the lancet needle out of the inner case, and is then moved rearward to the inner case.
