An electric wire protecting device is used in order to be capable of being installed in a narrow wiring area like one in a small aircraft, and to minimize a risk of an electric arc inside electric wire bundles at low costs. To this end, the electric wire protecting device includes: power wire groups each of which is an assembly of one or more power wires at the same potential; a tape for binding the power wire groups at different potentials from one another into one bundle at a constant pitch; and a spacer extending in a direction of extension of the power wire groups, and inserted in boundaries between the power wire groups.