Abstract: The present invention relates to a device for adjusting the injection timing of a distribution-type fuel injection pump for internal combustion engines. In the device of the present invention in which an adjusting piston is moved responsive to the fuel pressure in the high-pressure oil chamber and the resilient force of the timer spring, and the roller ring is rotated following the movement of the adjusting piston, the improvement comprises a cylinder which is provided in addition to a cylinder that accommodates the adjusting piston, and a shaft which slides in the above cylinder separately from the adjusting piston, so that the position of the adjusting piston can be adjusted by the shaft. The device employs sliding portions that do not require strict machining precision. Further, when the fuel injection pump is to be mounted on the engine, the initial timing can be easily adjusted through manipulation effected from the outer side of the fuel injection pump.