A linear stapler comprises a support base having a proximal end and a distal end； a trigger located at the proximal end of the support base； an end effector located at the distal end of the support base, fired by the trigger and including a cartridge. The cartridge comprises a cartridge body. The cartridge body includes staple slots for accommodating staples； and a cartridge lockout which is forced into an open position to abut against an outer side of a staple driver when the cartridge is not fired and which springs back toward the inside direction of the cartridge body after the staples in the cartridge are fired by the staple driver. Another linear stapler comprises a support base having a proximal end and a distal end； a trigger located at the proximal end of the support base； an end effector located at the distal end of the support base, fired by the trigger and including a cartridge, the cartridge comprising a cartridge body including a spent cartridge indicator.
