A fastener driving tool is capable of not only linearly driving but also rotationally fastening a fastener into a workpiece P. The fastener driving tool includes a housing 2, a nose portion 40 formed with an injection passage 40a through which a fastener 41 is driven, a magazine 4 accommodating fasteners 41 and supplying a fastener 41 to the nose portion 40, a push lever 5 movable relative to the housing 2 upon depression against the workpiece P, combustion chamber frames 12, 22 movable in the housing 2 in accordance with the movement of the push lever 5, and first and second cylinders 7, 8 fixed to the housing 2. First and second pistons 71, 81 are movably disposed in the first and second cylinders 7,8, respectively, and a bit 9 extends from the first piston 71. A rod 14 formed with a rack 14A extends from the second piston 72. The rack 14A is engageable with a motion conversion mechanism 6 for converting a linear motion of the rod 14 into rotational motion of the bit 9.