PURPOSE: To prevent the surpercharge pressure from elevating when a waste gate valve is stuck, by providing a valve to a passage extending from a turbo- charger to a boost compensater, and cutting the action of surpercharge pressure when overboost has occurred.

CONSTITUTION: A valve apparatus 21 is provided to a passage between a turbo- charger 1 and a boost compensater 12 of a fuel jetting pump 11. A piston 27 is energized by a spring 29 in a sleeve 25 placed in a housing 22 of the valve apparatus 21 and is movable relatively to the sleeve 25. When a waste gate valve 7 is stuck, the supercharge pressure increases, and an overboost state has occurred, the spring 29 is constructed, a flange 27a of the piston 27 and the end section on the side port 23 of the sleeve 25 are engaged to close the communication passage 28. Thus, the supercharge pressure can be prevented from rising.