This study was conducted to investigate the diversity of higher fungi in NaeJangSan National Park from April 2004 to November 2006. The obtained results from investigation were as follows. The total of 5 classes, 19 orders, 60 families, 168 genera and 418 species (including 10 families, 13 genera and 15 species unrecorded) including saprophytic and ectomycorrhizal fungi was investigated. The higher fungi were classified into 47 families, 143 genera and 384 species in Basidiomycotina, 9 families, 19 genera and 28 species in Ascomycotina and 4 families, 6 genera and 6 species in Myxomycota. It was turned out that most of the higher fungi belong to Hymenomycetidae in Basidiomycotina, for which 34 families 122 genera, and 353 species were observed. Dorminant species belonged to Tricholomataceae(64 species) Russulaceae(39 species), Polyporaceae(36 species) and Boletaceae(36 species). The mushroom occurrence of higher fungi was closely related to climatic conditions such as high air temperature and lots of rainfall from July to September. The environment which has a favorable influence of mushroom occurrence was air temperature, relative humidity and rainfall of climatic environment.