PURPOSE: To restrain a starting time increase amount within a proper injection amount while an injection amount increase amount in a supercharging territory sufficiently large and to decrease smoke generated at the time of starting.

CONSTITUTION: A control sleeve 10 is linked with one end of a start lever 12. The start lever 12 and a tension lever 19 are supported by the same fulcum 13, and between both of them, a start spring 21 to energize the start lever 12 in the fuel increase direction is interposed. A start time increase amount regulation lever 22 is provided to regulate the maximum oscillation position of the start lever 12, and the lever 22 is held at a specified position by a set spring 23. At the time of starting without thrust of a mechanical governor 14, start time increase is carried out by energizing force of the start spring 21, but its increase amount is regulated by the start time increase amount regulation lever 22. As spring force of the set spring 23 is weak, movement of the tension lever 19 after completion of starting is not inhibited.