Modalen is a municipality in the Nordhordland district in the northern part of Hordaland county in Norway. The administrative centre of the municipality is the village of Mo. The other main village in the municipality is Øvre Helland. Modalen is very sparsely populated, in fact, only the municipality of Utsira has less inhabitants. Most of the residents of Modalen live in the main Modalen valley which extends eastwards from the end of the Romarheimsfjorden.