This invention is a write-once near-field optical medium using a zinc oxide nano-structured thin film as the localized near-field optical interaction layer. This write-once near-field optical medium is a multi-layered body at least comprising: (a) a substrate of transparent material; (b) a first protective and spacer layer formed on one surface of the substrate, which is made of transparent dielectric material; (c) a zinc oxide nano-structured thin film which is capable of causing localized near-field optical interactions; (d) a second protective and spacer layer formed on the localized near-field optical interaction layer, which is also made of transparent dielectric material; (e) a write-once recording layer; (f) a third protective and spacer layer formed on the write-once recording layer, which is also made of transparent dielectric material. Ultra-high density near-field optical recording can be achieved by the localized near-field optical interactions of the zinc-oxide (ZnO) nano-structured thin film that is in the near-field region of the write-once recording layer.