provided is a technique for mass - producing a conductor to which is fixed a current detection head that detects the value of current flowing in the conductor , and in which the relationship between the detection value and the current value is stabilized . the head comprises a lens , a magneto - optical element , a conductor , and a fixing member , and the lens , the magneto - optical element , and the conductor are respectively fixed to the fixing member . an optical system is formed using the current detection head such that light is guided through the lens to the magneto - optical element , and light affected by a magneto - optical effect due to the magneto - optical element is guided to the lens . all of the members contributing to current detection are fixed to the fixing member , and therefore the relative positional relationships of all the members contributing to current detection are uniquely determined , enabling conductors with little variation in current detection characteristics to be mass - produced . a shape for determining the positional relationship between the fixing member and the conductor may be formed therebetween in advance , and the positioned current detection head and conductor may be fixed to obtain the conductor .