PURPOSE: To obtain an insulator-sealed type detector compactized for detecting voltage and current, by arranging a condenser voltage divider and a magnetic core close to a projection in a cavity of an insulator with a groove on the top thereof and a hollow section inside.

CONSTITUTION: In an insulator 1 with a groove 2 on the top thereof and a cavity 3 inside, a floating electrode 5 forming a condenser voltage divider and an earth electrode 6 are provided close to a projection 4 in the cavity with the groove section 2. A magnetic core 9 has two clearances and on photomagnetic sensor 10 is arranged on one clearance facing the other sandwiching the projection 4. Then, the electrodes 5 and 6 are connected to a photovoltage sensor 11, the respective optical fiber cables 7 are connected to the sensors 10 and 11 and then, to an external light source and photoelectric converter. In this manner, with the groove section 2 formed from an insulator top surface, a wire for measuring voltage and current can be lowered at an intermediate position in a vertical way of the intermediate position. This allows the condenser voltage divider and the magnetic core 9 to be housed into a cavity 3 in a sorted manner thereby enabling a smaller size as a whole.