PURPOSE: To obtain a highly accurate electric quantity measuring unit in which the assembling work is facilitated by securing a current-magnetism converting means and a substrate directly to an input means thereby facilitating the positioning of a magnetoelectric converting means on the substrate and the current-magnetism converting means.

CONSTITUTION: A core 11 and a PC board 5 can be secured by simply inserting them into containing grooves made in a terminal block 14. At that time, magnetic field generated from the core 11 can be applied sufficiently to a magnetoelectric converting element 10 mounted on the PC board 5. When the core 11 is inserted into a groove while penetrating a terminal metal 16 vertically and the PC board 5 is inserted into a board containing groove 18 made in the block 14, the element 10 is arranged substantially perpendicularly to the air gap part of the core 11 and thereby the assembling work is improved and the accuracy is enhanced. The influence of external field can be eliminated by arranging a core shield 12 around the core 12. Assembling work is also simplified in this case because the shield 12 is simply inserted into the core shield containing groove of the block 14.