3b and 3c and the optical spacial transmission members 6a 6b and 6c are so long that the optical fibers 5a 5b and 5c can be arranged easily fig3 is a sectional view of the three phase collected type optical current transformer according to the second embodiment of the present invention in fig3 like reference numerals refer to like elements in fig1 the optical spacial transmission member 6 according to the second embodiment is a three phase collected type in which the optical spacial members 6a 6b and 6c in fig1 are collected into a single member within a single insulating cylinder the optical transmission member is connected with optical fibers 5a 5b and 5c corresponding to three phases in its upper end and connected with a concentrated optical fiber 11 collecting three phases in its lower end the concentrated optical fiber 11 is taken out so as to penetrate through an optical sealing terminal 10 as it is sealed in this embodiment the optical spacial transmission member 6 and the concentrated fiber 11 are adapted to collect three phases so that the diameter l 2 of the flange 1a formed in the common hermetically sealed container 1 can be made smaller than the diameter l 1 of the flange 1a in fig1 l 2 lt l 1 thereby miniaturizing the three phase collected type optical current transformer fig4 is a sectional view of the three phase collected type optical current transformer according to the third embodiment of the present invention fig5 is a sectional view taken on line v v in fig4 this embodiment is different from the first embodiment in that the optical.