In a power-driven backpack type machine including a main body having an internal combustion engine serving as a power source, a throttle lever device including a boss pivotably connected to one side of the main body an arm extending from the boss, and a throttle lever supported at a forward end of the arm for controlling the operation of the internal combustion engine. Locking means is provided for selectively lockingly securing the boss to the main body in a position in which the arm is upright and substantially parallel to the vertical longitudinal axis of the main body and in a position in which the arm extends forwardly of the main body. Resilient pressing means forces the boss against the main body with an adjustable biasing force which is adjusted by adjusting means.
