A linear cutting stapler includes an upper jaw and a lower jaw capable of closing or opening relative to each other. A staple cartridge is disposed at a distal end of the lower jaw. The lower jaw is U-shaped, and has a staple driving rod and a blade driving rod slidably disposed therein. The linear cutting stapler further includes a safety mechanism which includes an engagement member. A notch fitting the engagement member is disposed on a bottom surface of the staple driving rod. The safety mechanism further includes a floating block which is displaceable in the lower jaw in an up-down direction perpendicular to the length direction of the lower jaw. When the floating block is pressed against the staple cartridge or an anvil, a top end of the engagement member is driven to displace in the up-down direction, thus the engagement member is separated from the notch.