An injection control apparatus for a diesel engine, comprising: an injector for injecting fuel which is accumulated under pressure toward a combustion chamber upon opening of a solenoid valve; an injector driver for supplying a current to an electromagnetic actuator which controls an opening operation and a closing operation of the solenoid valve; a plurality of state detection units (s) for detecting a state of an engine or a state of an ambient environment; a valve opening control unit for supplying, to the electromagnetic actuator, a first current for opening the solenoid valve; an opened-state maintaining control unit for supplying, to the electromagnetic actuator, a second current for maintaining the solenoid valve, which is opened by the valve opening control unit, continuously in an opened position; and a timing control unit for variably adjusting a period of time from a starting time of the valve opening control unit to a time when the opened-state maintaining control unit becomes active in place of the valve opening control unit, in accordance with a result of detection provided by the state detection units (s), wherein the plurality of state detection units (s) comprise a water temperature gauge, a fuel pressure sensor for measuring common rail pressure, a fuel temperature detection sensor, and a voltmeter for measuring a voltage of a battery, and each of these are used to detect the state of the engine or of the ambient environment, wherein there is a standard time of the period of time from a starting time of the valve opening control unit to a time when the opened-state maintaining control unit becomes active in place of the valve opening control unit, and wherein; said period of time is made longer than the standard time when the water temperature gauge detects a low water temperature, and said period of time is made shorter than the standard time when the water temperature gauge detects a high water temperature; said period of time is made longer than the standard time when the fuel pressure sensor detects a low common rail pressure, and said period of time is made shorter than the standard time when the fuel pressure sensor detects a high common rail pressure; said period of time is made longer than the standard time when the fuel temperature detection sensor detects a low temperature of fuel in a fuel tank, and said period of time is made shorter than the standard time when the fuel temperature detection sensor detects a high temperature of fuel in a fuel tank, and; said period of time is made longer than the standard time when the voltmeter detects a low voltage of the battery, and said period of time is made shorter than the standard time when the voltmeter detects a high voltage of the battery. an injector for injecting fuel which is accumulated under pressure toward a combustion chamber upon opening of a solenoid valve; an injector driver for supplying a current to an electromagnetic actuator which controls an opening operation and a closing operation of the solenoid valve; a plurality of state detection units (s) for detecting a state of an engine or a state of an ambient environment; a valve opening control unit for supplying, to the electromagnetic actuator, a first current for opening the solenoid valve; an opened-state maintaining control unit for supplying, to the electromagnetic actuator, a second current for maintaining the solenoid valve, which is opened by the valve opening control unit, continuously in an opened position; and a timing control unit for variably adjusting a period of time from a starting time of the valve opening control unit to a time when the opened-state maintaining control unit becomes active in place of the valve opening control unit, in accordance with a result of detection provided by the state detection units (s), wherein the plurality of state detection units (s) comprise a water temperature gauge, a fuel pressure sensor for measuring common rail pressure, a fuel temperature detection sensor, and a voltmeter for measuring a voltage of a battery, and each of these are used to detect the state of the engine or of the ambient environment, wherein there is a standard time of the period of time from a starting time of the valve opening control unit to a time when the opened-state maintaining control unit becomes active in place of the valve opening control unit, and wherein; said period of time is made longer than the standard time when the water temperature gauge detects a low water temperature, and said period of time is made shorter than the standard time when the water temperature gauge detects a high water temperature; said period of time is made longer than the standard time when the fuel pressure sensor detects a low common rail pressure, and said period of time is made shorter than the standard time when the fuel pressure sensor detects a high common rail pressure; said period of time is made longer than the standard time when the fuel temperature detection sensor detects a low temperature of fuel in a fuel tank, and said period of time is made shorter than the standard time when the fuel temperature detection sensor detects a high temperature of fuel in a fuel tank, and; said period of time is made longer than the standard time when the voltmeter detects a low voltage of the battery, and said period of time is made shorter than the standard time when the voltmeter detects a high voltage of the battery.