In a gas combustion type driving tool, on a feed cylinder 21 included in a feed piston/cylinder device 7, there is provided a spring for normally urging a feed piston 22 in a feed direction. A portion of the feed cylinder 21 opposite to the spring is connected to a combustion chamber 5 through a gas conduit 26. In an intermediate portion of the gas conduit 26, there is provided a delay piston/cylinder device A. One end of a delay cylinder 27 is disposed on the combustion chamber 5 side, while the other end thereof is disposed on the feed cylinder 21 side. When a delay piston 28 is slidingly moved from one end of the delay cylinder 27 to the other end thereof by the pressure of combustion gas, air compressed within the delay cylinder 27 is supplied from the other end of the delay cylinder 27 to the feed cylinder 21.