PURPOSE: To provide a regenerating arrangement unnecessary for much cost of a soot burn-off filter in an exhaust path of an air-compressing fuel injected internal combustion engine provided with a mechanical speed governor and an altitude matching device depending on the atmospheric pressure.

CONSTITUTION: In a housing 4 of an altitude matching device 3 to be communicated with the atmosphere by a vent pipe 9, a barometer capsule 5 is abutted on a thin film 11 in contact with stopper 15 by the spring force through a support plate 14. When the back pressure of the exhaust gas to be applied to a thin film chamber 12 connected to an exhaust path of an internal combustion engine having a soot burn-off filter through a exhaust gas back pressure piping 13 is increased, the thin film 11 and the barometer capsule 5 are displaced without changing the length of the barometer capsule 5. This displacement operates a governor lever 22 through a link mechanism in a speed governor 2, and operates a control rod 24 of a fuel injection pump in the reducing direction.