There are marked differences in climate condition between east-facing slopes and west-facing slopes in Mt. Seorak (1,708 m). This study was conducted to find out the differences of benthic macroinvertebrate communities between both slopes of Mt. Seorak. Quantitative (Surber net; $30cm{ imes}30cm$, mesh: 1mm) and qualitative (Hand net; mesh: 1mm) samplings ware carried out seasonally in each site which had 100-meter-high difference from November 2010 to November 2011. Most of the survey sites showed sound environmental conditions because they were located in the protection area of the national park. The benthic macroinvertebrates collected from all survey sites were composed of 158 species, 62 families, 17 orders, 7 classes and 5 phyla. DCA (Detrended Correspondence Analysis) ordination based on the abundance of benthic mactoinvertebrates showed that altitude was a major factor governing the structure of benthic macroinvertebrate community. There was no significant difference of the communities between both slopes.