NOVELTY - A fuel gas for driving a combustion type power tool, comprises at least 40% of 1-butene; and propane.    USE - The fuel gas is used for driving a combustion type power tool (claimed) for striking a fastening piece of a nail or a rivet. The combustion type power tool is for a gas nailing machine.    ADVANTAGE - The fuel gas is inexpensive, and does not deteriorate performance of a gas nailing machine. It can be vaporized even when the combustion type power tool is at low temperatures; and the combustion type power tool can be driven stably.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) a combustion type power tool comprising a housing (14); a head portion provided at a vicinity of an end of the housing, and formed with a fuel gas path; a cylinder (4) fixed to inside of the housing; a nose extended to a lower side from a lower end portion of the cylinder; a push lever (21) provided along the nose, and movable when the push lever is pressed to a workpiece; a piston (10) reciprocally slidable to the cylinder in an axial direction of the cylinder, and capable of partitioning the cylinder into a piston lower chamber and a piston upper chamber in the cylinder; a combustion chamber frame (15) movably guided at inside of the housing, and capable of being brought into contact with and being separated from the head portion in cooperation with movement of the push lever, the combustion chamber frame forming a combustion chamber with the head portion and the piston; and a connecting unit extended along a side face of the cylinder, for connecting the push lever and the combustion chamber frame, where combustion type power tool is driven by a fuel gas; and    (2) a compressed gas container (7) for a combustion type power tool, comprising an outer side vessel; an inner side vessel provided at inside of the outer side vessel, and the inner side vessel being filled with a fuel gas; a valve capable of injecting the fuel gas in the inner side vessel to outside of the outer side vessel; and a metering valve selectively connectable to the valve, the metering valve being capable of measuring an amount of injecting the fuel gas.    DESCRIPTION OF DRAWING(S) - The figure is a sectional view in a stationary state of a combustion type power tool.    Cylinder (4)    Compressed gas container (7)    Piston (10)    Housing (14)    Combustion chamber frame (15)    Push lever (21)