PURPOSE: A pharmaceutical composition containing Juncus effusus extract for preventing or treating inflammatory or immune disease is provided to suppress activation of NF-kappaB(nuclear factor kappa B) and expression of TNF-alpha(tumor necrossi factor-alpha) and NO(nitrogen oxide). CONSTITUTION: A composition for preventing or treating inflammatory or immune diseases contains Juncus effuses extract as an active ingredient. The composition for treating or preventing inflammatory or immune diseases contain canthoside derivative of chemical formula 1 or its pharmaceutically acceptable salt as an active ingredient. In the chemical formula 1, R1 to R5 independently H, OMe, COOMe or OH. The canthoside derivative is isolated from Juncus effuses using solvent. The solvent is water, methanol, ethanol, butanol, chloroform, hexane, ethylaceate, dichloromethane, or their mixture.본 발명은 염증질환 또는 면역질환의 치료 또는 예방에 유용한 약학 조성물에 관한 것으로서, 골풀(Juncuseffusus) 추출물, 바람직하게는, 칸토사이드, 보다 바람직하게는, 칸토사이드 B를 유효성분으로 포함하는 것을 특징으로 한다.