A working machine includes a throttle cable for transmitting an amount of operation of a throttle lever to a throttle valve, upper and lower guide rollers for guiding the throttle cable, and a throttle cable tightening/loosening means including a pivotable arm portion having a pressing roller located between the upper and lower guide rollers. The working machine further includes connecting means interconnecting the arm portion and a clutch lever. Operation of the clutch lever moves the pressing roller between a tightening position to tighten the throttle cable and a slackening position to slacken the throttle cable.