Eidskog is a municipality in Hedmark county, Norway. It is part of the traditional region of Glåmdal. The administrative centre of the municipality is the village of Skotterud. Eidskog was separated from the municipality of Vinger in 1864.
The municipality is located at the southern end of Hedmark county. It is bordered to the north by the municipality of Kongsvinger and in the west by Aurskog-Høland, Nes og Sør-Odal. Eidskog borders on Sweden, both to the east and south.
The Old Norse form of the name was Eiðaskógr. The first element is the plural genitive case of eið which means "path between two lakes". The last element is skógr which means "woods". Thus "the woods with the many eiðs". (In old times people travelled in small boats on the lakes and the rivers, but they had to drag the boats over the eids.)