In an injection control device for a fuel injection pump comprising: a water temperature sensor; a cold start device (CSD) for advancing a fuel injection timing to an engine when started up in a low temperature; and a controller, the controller recognizes a value T of water temperature by a signal from the water temperature sensor, and activates the CSD when the engine is started up and when the value of water temperature recognized by the controller (recognized value T of water temperature) is lower than a threshold value Tc of water temperature. If a value V of voltage of a power source of the controller becomes lower than a threshold value Vn of the voltage of the power source during activation of the CSD, a value Tn of water temperature recognized by the controller immediately before the value of voltage of the power source becomes lower than the threshold value of voltage of the power source is maintained as the value T of water temperature recognized by the controller for activating the cold start device.