To distinguish eddy current generated around cores in the early stage in connection with the valve system which drives the intake valve or the exhaust valve of an internal combustion engine by electromagnetic force.

A first core 34 holding a first electromagnetic coil 32 and a second core 38 holding a second electromagnetic coil 36 are disposed while being parted by a specified distance. A magnetic plate 30 to be connected with a valve body 12, is interposed between the first core 34 and the second core 38. A first slit which is extended from one end face to the other end face, and a second slit which is extended from the other end face to one end face, are provided for the first core 34 and the second core 38 respectively. The first and second slits are so provided that they donot penetrate through the first and second cores 34 and 38 in the axial direction, and however they are overlapped with each other.