To reduce the number of parts, to improve durability by preventing the occurrence of a failure in operation, and to prevent the generation of excessive black smoke during restarting after warming up of an engine.

A temperature-sensitive operating means 10 having a book 12 arranged at either one of a first lever 1a or a second lever 1b is fixed and the hook 12 is constituted to be displaced to a lock position E and a lock release position F based on the other lever. During cold starting, the hook 12 is displaced to the lock release position F and the first lever 1a is positioned in a starting increase position ST. After warming up of an engine, the hook 12 is displaced to the lock position E and it is blocked that the first lever 1a overshoots a torque up regulation area Q toward the fuel increase side R.