Travelling to North Corea, you need valid passport (with its longest validity, as possible, it is recommended).
However, the individual tourist activity does not exist in North Corea, and tourist trips are permitted within scope of orgamized tourist activities only.
Travelling to North Corea, you need the respective entry visa, which could be obtained at Consular Section of North Corean Embassy abroad. The North Corean Embassy distinguish three types of entry visas, such as: diplomatic visas, standard/normal visas (business and visit) and tourist visas.
When entering the territory of North Corea, the foreigner is obliged to present: his valid passport and fill in the respective entry/leaving forms. So called announcing duty is existing in North Corea.
Provided some of duties could not be maintained, so high severe penalties could follow. The respective registration is being arranged by host organization.
Information and warnings on travelling abroad is to be found HERE.