An improved portable work bench includes a structural body, and a platform disposed on the structural body. In addition, the platform includes a cam mechanism for locking the position of the platform along the structural body. Further, the portable work bench may include a plurality of legs for supporting the structural body. The structural body may be tubular and preferably has a square cross-section. Accordingly, the user need only place the platform in any position along the length of the structural body and move the cam mechanism to lock the platform in place. The cam mechanism may include a cam pivotally attached to the platform near the structural body, so that when the user rotates the cam, the cam contacts the structural body, locking the platform. A plate may be disposed between the cam and the structural body. The plate may have a hook portion, which contacts the bottom surface of the structural body.