PURPOSE: To improve the structure of an electromagnetic valve for miniaturization as a whole by providing a stroke transmission chamber between a valve control cam and a valve shaft to cause an axial effective length to be changed by controlling the supply and discharge of a liquid with an electromagnetic valve.

CONSTITUTION: A valve controller arranged between a valve shaft 12 having a valve member 11 and a valve control cam 14 has a valve piston 25 and a cam piston 27, fitted to each other, in a casing hole 24 in a casing block 23 fitted into a control casing 20. A stroke transmission chamber 29 defined by the valve piston 25 and the piston portion 26 of the cam piston 27 and filled with oil is connected to a feed pump 34 via a conduit 30 and an electromagnetic valve 31. In this case, the electromagnetic valve 31 is formed so as to load a valve member formed as an accumulator piston 41 with a closing spring 45 and hold the valve member 41 at an opening position against the closing spring 45 with an permanent magnet 56 during non-exciting of the electromagnetic coil 52.