A safety scalpel is made of a blade shield, blade, blade holder and handle. The blade holder is located in the front portion of the handle and the blade holder and handle are of integral connection structure or separate plug type connection structure. The blade is fixed in the front portion of the blade holder and the blade shield is slidably mounted on the blade holder, wherein: the blade holder is provided with a first sliding channel and the first sliding channel is provided with a first front locking channel at its front end. A deadlock channel is set in front of the first front locking channel. The blade shield may be moved further forward after use to make the first protrusion of blade shield fall in deadlock channel to enter the deadlocking state. The construction thoroughly eliminates the safety problem of reusing scalpel.
