PURPOSE: To enlarge a controllable range by widely changing a fuel pressure in the vicinity of the pressure receiving surface of a servo valve by providing a pressure control means to regulate a fuel pressure in a low pressure chamber.

CONSTITUTION: To control an injection timing in the direction of an angle of lead, the opening of a solenoid valve 3 is controlled in a closing direction. Since the feed of fuel from a pump chamber A to a low pressure chamber 41L is disconnected, an indoor pressure is reduced by an amount equivalent to a fuel escaped through an orifice 11 to a low pressure port 10, a valve body 5b is moved to the right, and a roller holder, not shown, is rotated. To delay an injection timing, the opening of the solenoid valve 3 is controlled in an opening direction. A passage hole 110, a solenoid valve 3, and a passage hole 120 are interconnected and fuel in the pump chamber A flows in the lower pressure chamber 41L, an indoor pressure is increased, and the valve body 5b is moved to the left. Passage holes 45 and 101-103 are intercomunicated, fuel in a high pressure chamber 41H flows in the low pressure chamber 41L, an indoor pressure is increased, and a timer piston 4 is moved to the left in Fig. to rotate a roller holder.