A safe scaffold includes door type frames, crossbars, and toe boards. The door type frame has a ledger, located in the lower end, connected to standards that are parallel to each other and are installed with combined pins thereon individually. The crossbar includes joint bar members having engaging holes engaged with the combined pins of the door type frame, and connects one door type frame to another door type frame in a cross link method, or connected to other joint bar members through the engaging couplers. The toe board is provided on the ledgers of every two adjacent door type frames. The invention creates an available space for setting guardrails by lowering the position of the toe board of the scaffold, adjusts the position and combination of the crossbars to form guardrails, and reduces the gaps of side rails.