To provide an insulating spacer for a gas-insulated switchgear which is reliable over a long duration.

This insulation spacer is formed by die molding of an epoxy resin. The insulation spacer is manufactured by coating a embedded metal tool 4 of aluminum or an aluminum alloy for installation of the insulation spacer with an anodization film 5 in the whole surface area or the surface area of a region to be exposed out of the insulation spacer 1, after die molding to the boundary of being embedded in the epoxy resin and integrally embedding the resultant tool 4 in a prescribed position of a flange part 3.