The invention provides a fuel injection control device for an internal combustion engine that can improve the accuracy of combustion control regarding smoke suppression. The fuel injection control device is applied to an engine provided with an EGR device for returning, as a part of an intake gas flown into the cylinder, an EGR gas, withdrawn from an exhaust passage, to an air intake passage. The amount of oxygen OXM contained in the intake gas and the concentration of oxygen OXC contained in the intake gas are detected (steps S1 and S2). The smoke tolerable limit value QOXMLMT as the upper limit of the amount of fuel injection, which can suppress the amount of smoke generated in the engine to a predetermined tolerance range, is set based on the detected amount of oxygen and concentration of oxygen (step S4), and, when the required amount of injection QDMD determined based on operation conditions is larger than the tolerable limit value QOXMLMT, the instructional injection amount QFIN is limited to the tolerable limit value QOXMLMT.