PURPOSE: To readjust a regulating range by narrowing it without breaking a sealing means of a bolt withing an initial restricting range of a speed governing lever set by an engine speed restricting bolt.

CONSTITUTION: A board shape swinging restricting means 15 is made to face a speed adjusting plate 18 through a serration mechanism 30 with a pivotal shaft 19 of a speed governing lever 7 as its center so as to be rotatable relatively, and a regulating part 16 arranged in the circumferential direction of the swinging restricting means 15 is made to face so as to come into contact with a locking part 34 of the speed governing lever 7. When the swinging restricting means 15 is operated in rotation, since it comes into contact with the regulating part 16 before the speed governing lever 7 reaches a restricting position, a swinging range of the speed governing lever 7 can be regulated more narrowly without breaking a sealing means of a restricting bolt.