To provide a fuel amount adjusting device for a diesel engine, facilitating output adjusting work for the engine.

When an engine revolving speed is reduced down to a predetermined torque rise revolution region, unbalance force between torque rise spring force 14a and governor force 9a moves a fuel control rack 2 to control fuel to be increased as the engine revolving speed is reduced. When the engine revolving speed is reduced down to a predetermined reverse adaptation revolution region, unbalance force between torque rise spring force 14a and governor force 9a protrudes a large diameter portion 19 of a torque rise pin 13 from a holder 12 while rocking a governor force input lever 6 to increase the fuel. Thus, a peripheral thickness portion 25 of a pin insertion hole 21 is pushed by a near-rocking-center corner portion 24 at the front end of the large diameter portion 19 to rock a reverse adaptation lever 18 in stand-by attitude to reduce the fuel so that the fuel control rack 2 is moved to control the fuel to be reduced as the engine revolving speed is reduced.