PURPOSE: To simplify an arc horn device which can prevent bird damage, by making a middle arc horn main body in longitudinal direction parallel with an insulator train longitudinal direction, and also forming horn intervals which are along the insulator train longitudinal direction, respectively between the middle arc horn main body and main arc horns at both ends.

CONSTITUTION: A metal fitting 3 having a main arc horn 2a and a metal fitting 4 having a main arc horn 2b are provided on both end sides of a tension insulator train 1, and at the same time a middle arc horn 5 equipped with a middle arc horn main body 5a which is along a string 1 in longitudinal direction and whose purpose is for flash relay, is provided at its middle. And a horn interval Z1 and a horn interval Z2 which are along the train 1 in longitudinal direction, are formed respectively between the main body 5a and one horn 2a and between the body 5a and the other horn 2b. As a result, bird damage can be avoided, and at the same time an insulator device which is superior in arc extinction can be obtain at a comparatively inexpensive cost with favorable condition for transport and housing.